UPSTREAM: filelock: fix potential use-after-free in posix_lock_inode

[ Upstream commit 1b3ec4f7 ]

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.

Bug: 370263554
Fixes: 74f6f591 ("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>
Change-Id: I59f2653b8041f2d8397f5e95538432ac303f349a
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>