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filelock: fix potential use-after-free in posix_lock_inode

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[ Upstream commit 1b3ec4f7c03d4b07bad70697d7e2f4088d2cfe92 ]

Light Hsieh reported a KASAN UAF warning in trace_posix_lock_inode().
The request pointer had been changed earlier to point to a lock entry
that was added to the inode's list. However, before the tracepoint could
fire, another task raced in and freed that lock.

Fix this by moving the tracepoint inside the spinlock, which should
ensure that this doesn't happen.

Fixes: 74f6f5912693 ("locks: fix KASAN: use-after-free in trace_event_raw_event_filelock_lock")
Link: https://lore.kernel.org/linux-fsdevel/724ffb0a2962e912ea62bb0515deadf39c325112.camel@kernel.org/
Reported-by: Light Hsieh (謝明燈) <Light.Hsieh@mediatek.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240702-filelock-6-10-v1-1-96e766aadc98@kernel.org
Reviewed-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jeff Layton 2024-07-02 18:44:48 -04:00 • committed by Ksawlii
parent a66805274e
commit a13746ed11
1 changed files with 1 additions and 1 deletions
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2
fs/locks.c
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@ -1365,9 +1365,9 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
locks_wake_up_blocks(left);
}
out:
trace_posix_lock_inode(inode, request, error);
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
trace_posix_lock_inode(inode, request, error);
/*
* Free any unused locks.
*/