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If a filesystem returns negative inode sizes, future reads on the file were
causing the cpu to spin on truncate_pagecache.
Create a helper to validate the attributes. This now does two things:
- check the file mode
- check if the file size fits in i_size without overflowing
Reported-by: Arijit Banerjee <arijit@rubrik.com>
Fixes: d8a5ba45457e ("[PATCH] FUSE - core")
Cc: <stable@vger.kernel.org> # v2.6.14
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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With DEBUG_PAGEALLOC on, the following triggers.
BUG: unable to handle page fault for address: ffff88859367c000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 3001067 P4D 3001067 PUD 406d3a8067 PMD 406d30c067 PTE 800ffffa6c983060
Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
CPU: 38 PID: 3110657 Comm: python2.7
RIP: 0010:fuse_readdir+0x88f/0xe7a [fuse]
Code: 49 8b 4d 08 49 39 4e 60 0f 84 44 04 00 00 48 8b 43 08 43 8d 1c 3c 4d 01 7e 68 49 89 dc 48 03 5c 24 38 49 89 46 60 8b 44 24 30 <8b> 4b 10 44 29 e0 48 89 ca 48 83 c1 1f 48 83 e1 f8 83 f8 17 49 89
RSP: 0018:ffffc90035edbde0 EFLAGS: 00010286
RAX: 0000000000001000 RBX: ffff88859367bff0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88859367bfed RDI: 0000000000920907
RBP: ffffc90035edbe90 R08: 000000000000014b R09: 0000000000000004
R10: ffff88859367b000 R11: 0000000000000000 R12: 0000000000000ff0
R13: ffffc90035edbee0 R14: ffff889fb8546180 R15: 0000000000000020
FS: 00007f80b5f4a740(0000) GS:ffff889fffa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88859367c000 CR3: 0000001c170c2001 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
iterate_dir+0x122/0x180
__x64_sys_getdents+0xa6/0x140
do_syscall_64+0x42/0x100
entry_SYSCALL_64_after_hwframe+0x44/0xa9
It's in fuse_parse_cache(). %rbx (ffff88859367bff0) is fuse_dirent
pointer - addr + offset. FUSE_DIRENT_SIZE() is trying to dereference
namelen off of it but that derefs into the next page which is disabled
by pagealloc debug causing a PF.
This is caused by dirent->namelen being accessed before ensuring that
there's enough bytes in the page for the dirent. Fix it by pushing
down reclen calculation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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The old fuse_read_fill() helper can be deleted, now that the last user is
gone.
The fuse_io_args struct is moved to fuse_i.h so it can be shared between
readdir/read code.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Move this function to the readdir.c where its only caller resides.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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This continues previous patch and introduces the same protection for
nlookup field.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Use the internal iversion counter to make sure modifications of the
directory through this filesystem are not missed by the mtime check (due to
mtime granularity).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Store the modification time of the directory in the cache, obtained before
starting to fill the cache.
When reading the cache, verify that the directory hasn't changed, by
checking if current modification time is the same as the one stored in the
cache.
This only needs to be done when the current file position is at the
beginning of the directory, as mandated by POSIX.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Allow the cache to be invalidated when page(s) have gone missing. In this
case increment the version of the cache and reset to an empty state.
Add a version number to the directory stream in struct fuse_file as well,
indicating the version of the cache it's supposed to be reading. If the
cache version doesn't match the stream's version, then reset the stream to
the beginning of the cache.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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The cache is only used if it's completed, not while it's still being
filled; this constraint could be lifted later, if it turns out to be
useful.
Introduce state in struct fuse_file that indicates the position within the
cache. After a seek, reset the position to the beginning of the cache and
search the cache for the current position. If the current position is not
found in the cache, then fall back to uncached readdir.
It can also happen that page(s) disappear from the cache, in which case we
must also fall back to uncached readdir.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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This patch just adds the cache filling functions, which are invoked if
FOPEN_CACHE_DIR flag is set in the OPENDIR reply.
Cache reading and cache invalidation are added by subsequent patches.
The directory cache uses the page cache. Directory entries are packed into
a page in the same format as in the READDIR reply. A page only contains
whole entries, the space at the end of the page is cleared. The page is
locked while being modified.
Multiple parallel readdirs on the same directory can fill the cache; the
only constraint is that continuity must be maintained (d_off of last entry
points to position of current entry).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Prepare for cache filling by introducing a helper for emitting a single
directory entry.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Directory reading code is about to grow larger, so split it out from dir.c
into a new source file.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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