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filelock: Fix fcntl/close race recovery compat path

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commit f8138f2ad2 upstream.

When I wrote commit 3cad1bc010 ("filelock: Remove locks reliably when
fcntl/close race is detected"), I missed that there are two copies of the
code I was patching: The normal version, and the version for 64-bit offsets
on 32-bit kernels.
Thanks to Greg KH for stumbling over this while doing the stable
backport...

Apply exactly the same fix to the compat path for 32-bit kernels.

Fixes: c293621bbf ("[PATCH] stale POSIX lock handling")
Cc: stable@kernel.org
Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=2563
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20240723-fs-lock-recover-compatfix-v1-1-148096719529@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jann Horn
2024-07-23 17:03:56 +02:00
committed by Greg Kroah-Hartman
parent d2c0c43dc4
commit 4c43ad4ab4
1 changed files with 4 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/locks.c
+4 -5
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@@ -2656,8 +2656,9 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
error = do_lock_file_wait(filp, cmd, file_lock); error = do_lock_file_wait(filp, cmd, file_lock);
/* /*
* Attempt to detect a close/fcntl race and recover by releasing the * Detect close/fcntl races and recover by zapping all POSIX locks
* lock that was just acquired. There is no need to do that when we're * associated with this file and our files_struct, just like on
* filp_flush(). There is no need to do that when we're
* unlocking though, or for OFD locks. * unlocking though, or for OFD locks.
*/ */
if (!error && file_lock->fl_type != F_UNLCK && if (!error && file_lock->fl_type != F_UNLCK &&
@@ -2671,9 +2672,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
f = fcheck(fd); f = fcheck(fd);
spin_unlock(&current->files->file_lock); spin_unlock(&current->files->file_lock);
if (f != filp) { if (f != filp) {
file_lock->fl_type = F_UNLCK; locks_remove_posix(filp, &current->files);
error = do_lock_file_wait(filp, cmd, file_lock);
WARN_ON_ONCE(error);
error = -EBADF; error = -EBADF;
} }
} }