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filelock: fix potential use-after-free in posix_lock_inode

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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: 74f6f59126 ("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>
This commit is contained in:
Jeff Layton 2024-07-02 18:44:48 -04:00 committed by Christian Brauner
parent eeb17984e8
commit 1b3ec4f7c0
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1 changed files with 1 additions and 1 deletions
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2
fs/locks.c
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@ -1367,9 +1367,9 @@ retry:
locks_wake_up_blocks(&left->c);
}
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.
*/