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authorFilipe Manana <fdmanana@suse.com>2015-07-03 20:30:34 +0100
committerSasha Levin <sasha.levin@oracle.com>2016-04-22 20:38:30 -0400
commit5d6226fe6abbaf576328d6cbc8c5473f32428d68 (patch)
treed5cf06f1696ede9cddcfb9bd6e4274f8e2720beb /fs
parent95617b5e03996c9b76743c187d53849ae1c296a2 (diff)
downloadlinux-linaro-stable-5d6226fe6abbaf576328d6cbc8c5473f32428d68.tar.gz
Btrfs: fix list transaction->pending_ordered corruption
[ Upstream commit d3efe08400317888f559bbedf0e42cd31575d0ef ] When we call btrfs_commit_transaction(), we splice the list "ordered" of our transaction handle into the transaction's "pending_ordered" list, but we don't re-initialize the "ordered" list of our transaction handle, this means it still points to the same elements it used to before the splice. Then we check if the current transaction's state is >= TRANS_STATE_COMMIT_START and if it is we end up calling btrfs_end_transaction() which simply splices again the "ordered" list of our handle into the transaction's "pending_ordered" list, leaving multiple pointers to the same ordered extents which results in list corruption when we are iterating, removing and freeing ordered extents at btrfs_wait_pending_ordered(), resulting in access to dangling pointers / use-after-free issues. Similarly, btrfs_end_transaction() can end up in some cases calling btrfs_commit_transaction(), and both did a list splice of the transaction handle's "ordered" list into the transaction's "pending_ordered" without re-initializing the handle's "ordered" list, resulting in exactly the same problem. This produces the following warning on a kernel with linked list debugging enabled: [109749.265416] ------------[ cut here ]------------ [109749.266410] WARNING: CPU: 7 PID: 324 at lib/list_debug.c:59 __list_del_entry+0x5a/0x98() [109749.267969] list_del corruption. prev->next should be ffff8800ba087e20, but was fffffff8c1f7c35d (...) [109749.287505] Call Trace: [109749.288135] [<ffffffff8145f077>] dump_stack+0x4f/0x7b [109749.298080] [<ffffffff81095de5>] ? console_unlock+0x356/0x3a2 [109749.331605] [<ffffffff8104b3b0>] warn_slowpath_common+0xa1/0xbb [109749.334849] [<ffffffff81260642>] ? __list_del_entry+0x5a/0x98 [109749.337093] [<ffffffff8104b410>] warn_slowpath_fmt+0x46/0x48 [109749.337847] [<ffffffff81260642>] __list_del_entry+0x5a/0x98 [109749.338678] [<ffffffffa053e8bf>] btrfs_wait_pending_ordered+0x46/0xdb [btrfs] [109749.340145] [<ffffffffa058a65f>] ? __btrfs_run_delayed_items+0x149/0x163 [btrfs] [109749.348313] [<ffffffffa054077d>] btrfs_commit_transaction+0x36b/0xa10 [btrfs] [109749.349745] [<ffffffff81087310>] ? trace_hardirqs_on+0xd/0xf [109749.350819] [<ffffffffa055370d>] btrfs_sync_file+0x36f/0x3fc [btrfs] [109749.351976] [<ffffffff8118ec98>] vfs_fsync_range+0x8f/0x9e [109749.360341] [<ffffffff8118ecc3>] vfs_fsync+0x1c/0x1e [109749.368828] [<ffffffff8118ee1d>] do_fsync+0x34/0x4e [109749.369790] [<ffffffff8118f045>] SyS_fsync+0x10/0x14 [109749.370925] [<ffffffff81465197>] system_call_fastpath+0x12/0x6f [109749.382274] ---[ end trace 48e0d07f7c03d95a ]--- On a non-debug kernel this leads to invalid memory accesses, causing a crash. Fix this by using list_splice_init() instead of list_splice() in btrfs_commit_transaction() and btrfs_end_transaction(). Cc: stable@vger.kernel.org Fixes: 50d9aa99bd35 ("Btrfs: make sure logged extents complete in the current transaction V3" Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/transaction.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 7dce00b91a71..240019f36b2a 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -723,7 +723,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
if (!list_empty(&trans->ordered)) {
spin_lock(&info->trans_lock);
- list_splice(&trans->ordered, &cur_trans->pending_ordered);
+ list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
spin_unlock(&info->trans_lock);
}
@@ -1732,7 +1732,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
}
spin_lock(&root->fs_info->trans_lock);
- list_splice(&trans->ordered, &cur_trans->pending_ordered);
+ list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
spin_unlock(&root->fs_info->trans_lock);
atomic_inc(&cur_trans->use_count);