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what the hell is op_mutex for, BTW?
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* sanity checks belong before risky operation, not after it
* don't quit as soon as we'd found an entry
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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new helper: dir_relax(inode). Call when you are in location that will
_not_ be invalidated by directory modifications (block boundary, in case
of ext*). Returns whether the directory has survived (dropping i_mutex
allows rmdir to kill the sucker; if it returns false to us, ->iterate()
is obviously done)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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new helpers - dir_emit_dot(file, ctx, dentry), dir_emit_dotdot(file, ctx),
dir_emit_dots(file, ctx).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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ext2, ufs, minix, sysv
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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New method - ->iterate(file, ctx). That's the replacement for ->readdir();
it takes callback from ctx->actor, uses ctx->pos instead of file->f_pos and
calls dir_emit(ctx, ...) instead of filldir(data, ...). It does *not*
update file->f_pos (or look at it, for that matter); iterate_dir() does the
update.
Note that dir_emit() takes the offset from ctx->pos (and eventually
filldir_t will lose that argument).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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iterate_dir(): new helper, replacing vfs_readdir().
struct dir_context: contains the readdir callback (and will get more stuff
in it), embedded into whatever data that callback wants to deal with;
eventually, we'll be passing it to ->readdir() replacement instead of
(data,filldir) pair.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and single return is quite sufficient to get out of function, TYVM
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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io_remap_pfn_range() does all we need
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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io_remap_pfn_range() sets it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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io_remap_pfn_range() will set it just fine
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.
This means that 'file->private_data' can be freed while 'ubifs_readdir()' uses
it, and this is a very bad bug: not only 'ubifs_readdir()' can return garbage,
but this may corrupt memory and lead to all kinds of problems like crashes an
security holes.
This patch fixes the problem by using the 'file->f_version' field, which
'->llseek()' always unconditionally sets to zero. We set it to 1 in
'ubifs_readdir()' and whenever we detect that it became 0, we know there was a
seek and it is time to clear the state saved in 'file->private_data'.
I tested this patch by writing a user-space program which runds readdir and
seek in parallell. I could easily crash the kernel without these patches, but
could not crash it with these patches.
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.
First of all, this means that 'file->private_data' can be freed while
'ubifs_readdir()' uses it. But this particular patch does not fix the problem.
This patch is only a preparation, and the fix will follow next.
In this patch we make 'ubifs_readdir()' stop using 'file->f_pos' directly,
because 'file->f_pos' can be changed by '->llseek()' at any point. This may
lead 'ubifs_readdir()' to returning inconsistent data: directory entry names
may correspond to incorrect file positions.
So here we introduce a local variable 'pos', read 'file->f_pose' once at very
the beginning, and then stick to 'pos'. The result of this is that when
'ubifs_dir_llseek()' changes 'file->f_pos' while we are in the middle of
'ubifs_readdir()', the latter "wins".
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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dump_seek() does SEEK_CUR, not SEEK_SET; native binfmt_aout
handles it correctly (seeks by PAGE_SIZE - sizeof(struct user),
getting the current position to PAGE_SIZE), compat one seeks
by PAGE_SIZE and ends up at PAGE_SIZE + already written...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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When you copy some code, you are supposed to read it. If nothing else,
there's a chance to spot and fix an obvious bug instead of sharing it...
X-Song: "I Got It From Agnes", by Tom Lehrer
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[ Tom Lehrer? You're dating yourself, Al ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC fixes from Olof Johansson:
"These are a little later than I planned on since I got caught up with
handling merges for 3.11 most of the week.
Another week, another batch of fixes for arm-soc platforms.
Again, nothing controversial. A few more than would be ideal, but all
are valid fixes. In particular the prima2 panic patch is critical
since it fixes a problem where multiplatform kernels panic on all but
prima2 hardware."
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
ARM: SAMSUNG: pm: Adjust for pinctrl- and DT-enabled platforms
ARM: prima2: fix incorrect panic usage
arm: mvebu: armada-xp-{gp,openblocks-ax3-4}: specify PCIe range
ARM: Kirkwood: handle mv88f6282 cpu in __kirkwood_variant().
ARM: omap3: clock: fix wrong container_of in clock36xx.c
ARM: dts: OMAP5: Fix missing PWM capability to timer nodes
ARM: dts: omap4-panda|sdp: Fix mux for twl6030 IRQ pin and msecure line
ARM: dts: AM33xx: Fix properties on gpmc node
arm: omap2: fix AM33xx hwmod infos for UART2
ARM: OMAP3: Fix iva2_pwrdm settings for 3703
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Pull networking fixes from David Miller:
1) Fix RTNL locking in batman-adv, from Matthias Schiffer.
2) Don't allow non-passthrough macvlan devices to set NOPROMISC via
netlink, otherwise we can end up with corrupted promisc counter
values on the device. From Michael S Tsirkin.
3) Fix stmmac driver build with debugging defines enabled, from Dinh
Nguyen.
4) Make sure name string we give in socket address in AF_PACKET is NULL
terminated, from Daniel Borkmann.
5) Fix leaking of two uninitialized bytes of memory to userspace in
l2tp, from Guillaume Nault.
6) Clear IPCB(skb) before tunneling otherwise we touch dangling IP
options state and crash. From Saurabh Mohan.
7) Fix suspend/resume for davinci_mdio by using suspend_late and
resume_early. From Mugunthan V N.
8) Don't tag ip_tunnel_init_net and ip_tunnel_delete_net with
__net_{init,exit}, they can be called outside of those contexts.
From Eric Dumazet.
9) Fix RX length error in sh_eth driver, from Yoshihiro Shimoda.
10) Fix missing sctp_outq initialization in some code paths of SCTP
stack, from Neil Horman.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (21 commits)
sctp: fully initialize sctp_outq in sctp_outq_init
netiucv: Hold rtnl between name allocation and device registration.
tulip: Properly check dma mapping result
net: sh_eth: fix incorrect RX length error if R8A7740
ip_tunnel: remove __net_init/exit from exported functions
drivers: net: davinci_mdio: restore mdio clk divider in mdio resume
drivers: net: davinci_mdio: moving mdio resume earlier than cpsw ethernet driver
net/ipv4: ip_vti clear skb cb before tunneling.
tg3: Wait for boot code to finish after power on
l2tp: Fix sendmsg() return value
l2tp: Fix PPP header erasure and memory leak
bonding: fix igmp_retrans type and two related races
bonding: reset master mac on first enslave failure
packet: packet_getname_spkt: make sure string is always 0-terminated
net: ethernet: stmicro: stmmac: Fix compile error when STMMAC_XMIT_DEBUG used
be2net: Fix 32-bit DMA Mask handling
xen-netback: don't de-reference vif pointer after having called xenvif_put()
macvlan: don't touch promisc without passthrough
batman-adv: Don't handle address updates when bla is disabled
batman-adv: forward late OGMs from best next hop
...
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git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
Pull powerpc fixes from Benjamin Herrenschmidt:
"So here are 3 fixes still for 3.10. Fixes are simple, bugs are nasty
(though not recent regressions, nasty enough) and all targeted at
stable"
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
powerpc: Fix missing/delayed calls to irq_work
powerpc: Fix emulation of illegal instructions on PowerNV platform
powerpc: Fix stack overflow crash in resume_kernel when ftracing
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Thanks to commit f91eb62f71b3 ("init: scream bloody murder if interrupts
are enabled too early"), "bloody murder" is now being screamed.
With a MIPS OCTEON config, we use on_each_cpu() in our
irq_chip.irq_bus_sync_unlock() function. This gets called in early as a
result of the time_init() call. Because the !SMP version of
on_each_cpu() unconditionally enables irqs, we get:
WARNING: at init/main.c:560 start_kernel+0x250/0x410()
Interrupts were enabled early
CPU: 0 PID: 0 Comm: swapper Not tainted 3.10.0-rc5-Cavium-Octeon+ #801
Call Trace:
show_stack+0x68/0x80
warn_slowpath_common+0x78/0xb0
warn_slowpath_fmt+0x38/0x48
start_kernel+0x250/0x410
Suggested fix: Do what we already do in the SMP version of
on_each_cpu(), and use local_irq_save/local_irq_restore. Because we
need a flags variable, make it a static inline to avoid name space
issues.
[ Change from v1: Convert on_each_cpu to a static inline function, add
#include <linux/irqflags.h> to avoid build breakage on some files.
on_each_cpu_mask() and on_each_cpu_cond() suffer the same problem as
on_each_cpu(), but they are not causing !SMP bugs for me, so I will
defer changing them to a less urgent patch. ]
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull VFS fixes from Al Viro:
"Several fixes + obvious cleanup (you've missed a couple of open-coded
can_lookup() back then)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
snd_pcm_link(): fix a leak...
use can_lookup() instead of direct checks of ->i_op->lookup
move exit_task_namespaces() outside of exit_notify()
fput: task_work_add() can fail if the caller has passed exit_task_work()
ncpfs: fix rmdir returns Device or resource busy
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Pull xfs fixes from Ben Myers:
- Remove noisy warnings about experimental support which spams the logs
- Add padding to align directory and attr structures correctly
- Set block number on child buffer on a root btree split
- Disable verifiers during log recovery for non-CRC filesystems
* tag 'for-linus-v3.10-rc6' of git://oss.sgi.com/xfs/xfs:
xfs: don't shutdown log recovery on validation errors
xfs: ensure btree root split sets blkno correctly
xfs: fix implicit padding in directory and attr CRC formats
xfs: don't emit v5 superblock warnings on write
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc fixes from Greg Kroah-Hartman:
"Here are some small mei driver fixes for 3.10-rc6 that fix some
reported problems"
* tag 'char-misc-3.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
mei: me: clear interrupts on the resume path
mei: nfc: fix nfc device freeing
mei: init: Flush scheduled work before resetting the device
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg Kroah-Hartman:
"Here are some small USB driver fixes that resolve some reported
problems for 3.10-rc6
Nothing major, just 3 USB serial driver fixes, and two chipidea fixes"
* tag 'usb-3.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
usb: chipidea: fix id change handling
usb: chipidea: fix no transceiver case
USB: pl2303: fix device initialisation at open
USB: spcp8x5: fix device initialisation at open
USB: f81232: fix device initialisation at open
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When replaying interrupts (as a result of the interrupt occurring
while soft-disabled), in the case of the decrementer, we are exclusively
testing for a pending timer target. However we also use decrementer
interrupts to trigger the new "irq_work", which in this case would
be missed.
This change the logic to force a replay in both cases of a timer
boundary reached and a decrementer interrupt having actually occurred
while disabled. The former test is still useful to catch cases where
a CPU having been hard-disabled for a long time completely misses the
interrupt due to a decrementer rollover.
CC: <stable@vger.kernel.org> [v3.4+]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
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Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr). The emulation of unimplemented instructions is currently not
working on the PowerNV platform. The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt. This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt(). With this, old programs that use no-longer
implemented instructions such as dcba now work again.
CC: <stable@vger.kernel.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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It's possible for us to crash when running with ftrace enabled, eg:
Bad kernel stack pointer bffffd12 at c00000000000a454
cpu 0x3: Vector: 300 (Data Access) at [c00000000ffe3d40]
pc: c00000000000a454: resume_kernel+0x34/0x60
lr: c00000000000335c: performance_monitor_common+0x15c/0x180
sp: bffffd12
msr: 8000000000001032
dar: bffffd12
dsisr: 42000000
If we look at current's stack (paca->__current->stack) we see it is
equal to c0000002ecab0000. Our stack is 16K, and comparing to
paca->kstack (c0000002ecab3e30) we can see that we have overflowed our
kernel stack. This leads to us writing over our struct thread_info, and
in this case we have corrupted thread_info->flags and set
_TIF_EMULATE_STACK_STORE.
Dumping the stack we see:
3:mon> t c0000002ecab0000
[c0000002ecab0000] c00000000002131c .performance_monitor_exception+0x5c/0x70
[c0000002ecab0080] c00000000000335c performance_monitor_common+0x15c/0x180
--- Exception: f01 (Performance Monitor) at c0000000000fb2ec .trace_hardirqs_off+0x1c/0x30
[c0000002ecab0370] c00000000016fdb0 .trace_graph_entry+0xb0/0x280 (unreliable)
[c0000002ecab0410] c00000000003d038 .prepare_ftrace_return+0x98/0x130
[c0000002ecab04b0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
[c0000002ecab0520] c0000000000d6b58 .idle_cpu+0x18/0x90
[c0000002ecab05a0] c00000000000a934 .return_to_handler+0x0/0x34
[c0000002ecab0620] c00000000001e660 .timer_interrupt+0x160/0x300
[c0000002ecab06d0] c0000000000025dc decrementer_common+0x15c/0x180
--- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0
[c0000002ecab09c0] c0000000000fe044 .trace_hardirqs_on+0x14/0x30 (unreliable)
[c0000002ecab0fb0] c00000000016fe3c .trace_graph_entry+0x13c/0x280
[c0000002ecab1050] c00000000003d038 .prepare_ftrace_return+0x98/0x130
[c0000002ecab10f0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
[c0000002ecab1160] c0000000000161f0 .__ppc64_runlatch_on+0x10/0x40
[c0000002ecab11d0] c00000000000a934 .return_to_handler+0x0/0x34
--- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0
... and so on
__ppc64_runlatch_on() is called from RUNLATCH_ON in the exception entry
path. At that point the irq state is not consistent, ie. interrupts are
hard disabled (by the exception entry), but the paca soft-enabled flag
may be out of sync.
This leads to the local_irq_restore() in trace_graph_entry() actually
enabling interrupts, which we do not want. Because we have not yet
reprogrammed the decrementer we immediately take another decrementer
exception, and recurse.
The fix is twofold. Firstly make sure we call DISABLE_INTS before
calling RUNLATCH_ON. The badly named DISABLE_INTS actually reconciles
the irq state in the paca with the hardware, making it safe again to
call local_irq_save/restore().
Although that should be sufficient to fix the bug, we also mark the
runlatch routines as notrace. They are called very early in the
exception entry and we are asking for trouble tracing them. They are
also fairly uninteresting and tracing them just adds unnecessary
overhead.
[ This regression was introduced by fe1952fc0afb9a2e4c79f103c08aef5d13db1873
"powerpc: Rework runlatch code" by myself --BenH
]
CC: <stable@vger.kernel.org> [v3.4+]
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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in case when snd_pcm_stream_linked(substream) is true, we end up leaking
group.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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a couple of places got missed back when Linus has introduced that one...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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exit_notify() does exit_task_namespaces() after
forget_original_parent(). This was needed to ensure that ->nsproxy
can't be cleared prematurely, an exiting child we are going to
reparent can do do_notify_parent() and use the parent's (ours) pid_ns.
However, after 32084504 "pidns: use task_active_pid_ns in
do_notify_parent" ->nsproxy != NULL is no longer needed, we rely
on task_active_pid_ns().
Move exit_task_namespaces() from exit_notify() to do_exit(), after
exit_fs() and before exit_task_work().
This solves the problem reported by Andrey, free_ipc_ns()->shm_destroy()
does fput() which needs task_work_add().
Note: this particular problem can be fixed if we change fput(), and
that change makes sense anyway. But there is another reason to move
the callsite. The original reason for exit_task_namespaces() from
the middle of exit_notify() was subtle and it has already gone away,
now this looks confusing. And this allows us do simplify exit_notify(),
we can avoid unlock/lock(tasklist) and we can use ->exit_state instead
of PF_EXITING in forget_original_parent().
Reported-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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fput() assumes that it can't be called after exit_task_work() but
this is not true, for example free_ipc_ns()->shm_destroy() can do
this. In this case fput() silently leaks the file.
Change it to fallback to delayed_fput_work if task_work_add() fails.
The patch looks complicated but it is not, it changes the code from
if (PF_KTHREAD) {
schedule_work(...);
return;
}
task_work_add(...)
to
if (!PF_KTHREAD) {
if (!task_work_add(...))
return;
/* fallback */
}
schedule_work(...);
As for shm_destroy() in particular, we could make another fix but I
think this change makes sense anyway. There could be another similar
user, it is not safe to assume that task_work_add() can't fail.
Reported-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Unfortunately, we cannot guarantee that items logged multiple times
and replayed by log recovery do not take objects back in time. When
they are taken back in time, the go into an intermediate state which
is corrupt, and hence verification that occurs on this intermediate
state causes log recovery to abort with a corruption shutdown.
Instead of causing a shutdown and unmountable filesystem, don't
verify post-recovery items before they are written to disk. This is
less than optimal, but there is no way to detect this issue for
non-CRC filesystems If log recovery successfully completes, this
will be undone and the object will be consistent by subsequent
transactions that are replayed, so in most cases we don't need to
take drastic action.
For CRC enabled filesystems, leave the verifiers in place - we need
to call them to recalculate the CRCs on the objects anyway. This
recovery problem can be solved for such filesystems - we have a LSN
stamped in all metadata at writeback time that we can to determine
whether the item should be replayed or not. This is a separate piece
of work, so is not addressed by this patch.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 9222a9cf86c0d64ffbedf567412b55da18763aa3)
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For CRC enabled filesystems, the BMBT is rooted in an inode, so it
passes through a different code path on root splits than the
freespace and inode btrees. This is much less traversed by xfstests
than the other trees. When testing on a 1k block size filesystem,
I've been seeing ASSERT failures in generic/234 like:
XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_private.b.allocated == 0, file: fs/xfs/xfs_btree.c, line: 317
which are generally preceded by a lblock check failure. I noticed
this in the bmbt stats:
$ pminfo -f xfs.btree.block_map
xfs.btree.block_map.lookup
value 39135
xfs.btree.block_map.compare
value 268432
xfs.btree.block_map.insrec
value 15786
xfs.btree.block_map.delrec
value 13884
xfs.btree.block_map.newroot
value 2
xfs.btree.block_map.killroot
value 0
.....
Very little coverage of root splits and merges. Indeed, on a 4k
filesystem, block_map.newroot and block_map.killroot are both zero.
i.e. the code is not exercised at all, and it's the only generic
btree infrastructure operation that is not exercised by a default run
of xfstests.
Turns out that on a 1k filesystem, generic/234 accounts for one of
those two root splits, and that is somewhat of a smoking gun. In
fact, it's the same problem we saw in the directory/attr code where
headers are memcpy()d from one block to another without updating the
self describing metadata.
Simple fix - when copying the header out of the root block, make
sure the block number is updated correctly.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit ade1335afef556df6538eb02e8c0dc91fbd9cc37)
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Michael L. Semon has been testing CRC patches on a 32 bit system and
been seeing assert failures in the directory code from xfs/080.
Thanks to Michael's heroic efforts with printk debugging, we found
that the problem was that the last free space being left in the
directory structure was too small to fit a unused tag structure and
it was being corrupted and attempting to log a region out of bounds.
Hence the assert failure looked something like:
.....
#5 calling xfs_dir2_data_log_unused() 36 32
#1 4092 4095 4096
#2 8182 8183 4096
XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568
Where #1 showed the first region of the dup being logged (i.e. the
last 4 bytes of a directory buffer) and #2 shows the corrupt values
being calculated from the length of the dup entry which overflowed
the size of the buffer.
It turns out that the problem was not in the logging code, nor in
the freespace handling code. It is an initial condition bug that
only shows up on 32 bit systems. When a new buffer is initialised,
where's the freespace that is set up:
[ 172.316249] calling xfs_dir2_leaf_addname() from xfs_dir_createname()
[ 172.316346] #9 calling xfs_dir2_data_log_unused()
[ 172.316351] #1 calling xfs_trans_log_buf() 60 63 4096
[ 172.316353] #2 calling xfs_trans_log_buf() 4094 4095 4096
Note the offset of the first region being logged? It's 60 bytes into
the buffer. Once I saw that, I pretty much knew that the bug was
going to be caused by this.
Essentially, all direct entries are rounded to 8 bytes in length,
and all entries start with an 8 byte alignment. This means that we
can decode inplace as variables are naturally aligned. With the
directory data supposedly starting on a 8 byte boundary, and all
entries padded to 8 bytes, the minimum freespace in a directory
block is supposed to be 8 bytes, which is large enough to fit a
unused data entry structure (6 bytes in size). The fact we only have
4 bytes of free space indicates a directory data block alignment
problem.
And what do you know - there's an implicit hole in the directory
data block header for the CRC format, which means the header is 60
byte on 32 bit intel systems and 64 bytes on 64 bit systems. Needs
padding. And while looking at the structures, I found the same
problem in the attr leaf header. Fix them both.
Note that this only affects 32 bit systems with CRCs enabled.
Everything else is just fine. Note that CRC enabled filesystems created
before this fix on such systems will not be readable with this fix
applied.
Reported-by: Michael L. Semon <mlsemon35@gmail.com>
Debugged-by: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 8a1fd2950e1fe267e11fc8c85dcaa6b023b51b60)
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