From f6f8285132907757ef84ef8dae0a1244b8cde6ac Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 17 Nov 2011 12:58:07 -0800 Subject: pstore: pass allocated memory region back to caller The buf_lock cannot be held while populating the inodes, so make the backend pass forward an allocated and filled buffer instead. This solves the following backtrace. The effect is that "buf" is only ever used to notify the backends that something was written to it, and shouldn't be used in the read path. To replace the buf_lock during the read path, isolate the open/read/close loop with a separate mutex to maintain serialized access to the backend. Note that is is up to the pstore backend to cope if the (*write)() path is called in the middle of the read path. [ 59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847 [ 59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount [ 59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1 [ 59.691019] Call Trace: [ 59.691019] [<810252d5>] __might_sleep+0xc3/0xca [ 59.691019] [<810a26e6>] kmem_cache_alloc+0x32/0xf3 [ 59.691019] [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4 [ 59.691019] [<810b68b1>] alloc_inode+0x2a/0x64 [ 59.691019] [<810b6903>] new_inode+0x18/0x43 [ 59.691019] [<81142447>] pstore_get_inode.isra.1+0x11/0x98 [ 59.691019] [<81142623>] pstore_mkfile+0xae/0x26f [ 59.691019] [<810a2a66>] ? kmem_cache_free+0x19/0xb1 [ 59.691019] [<8116c821>] ? ida_get_new_above+0x140/0x158 [ 59.691019] [<811708ea>] ? __init_rwsem+0x1e/0x2c [ 59.691019] [<810b67e8>] ? inode_init_always+0x111/0x1b0 [ 59.691019] [<8102127e>] ? should_resched+0xd/0x27 [ 59.691019] [<8137977f>] ? _cond_resched+0xd/0x21 [ 59.691019] [<81142abf>] pstore_get_records+0x52/0xa7 [ 59.691019] [<8114254b>] pstore_fill_super+0x7d/0x91 [ 59.691019] [<810a7ff5>] mount_single+0x46/0x82 [ 59.691019] [<8114231a>] pstore_mount+0x15/0x17 [ 59.691019] [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98 [ 59.691019] [<810a8199>] mount_fs+0x5a/0x12d [ 59.691019] [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a [ 59.691019] [<810b9474>] vfs_kern_mount+0x4f/0x7d [ 59.691019] [<810b9d7e>] do_kern_mount+0x34/0xb2 [ 59.691019] [<810bb15f>] do_mount+0x5fc/0x64a [ 59.691019] [<810912fb>] ? strndup_user+0x2e/0x3f [ 59.691019] [<810bb3cb>] sys_mount+0x66/0x99 [ 59.691019] [<8137b537>] sysenter_do_call+0x12/0x26 Signed-off-by: Kees Cook Signed-off-by: Tony Luck --- fs/pstore/platform.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'fs/pstore') diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 2bd620f0d796..57bbf9078ac8 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -167,6 +167,7 @@ int pstore_register(struct pstore_info *psi) } psinfo = psi; + mutex_init(&psinfo->read_mutex); spin_unlock(&pstore_lock); if (owner && !try_module_get(owner)) { @@ -195,30 +196,32 @@ EXPORT_SYMBOL_GPL(pstore_register); void pstore_get_records(int quiet) { struct pstore_info *psi = psinfo; + char *buf = NULL; ssize_t size; u64 id; enum pstore_type_id type; struct timespec time; int failed = 0, rc; - unsigned long flags; if (!psi) return; - spin_lock_irqsave(&psinfo->buf_lock, flags); + mutex_lock(&psi->read_mutex); rc = psi->open(psi); if (rc) goto out; - while ((size = psi->read(&id, &type, &time, psi)) > 0) { - rc = pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size, + while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) { + rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size, time, psi); + kfree(buf); + buf = NULL; if (rc && (rc != -EEXIST || !quiet)) failed++; } psi->close(psi); out: - spin_unlock_irqrestore(&psinfo->buf_lock, flags); + mutex_unlock(&psi->read_mutex); if (failed) printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n", -- cgit v1.2.3-58-ga151