From: Jann Horn jannh@google.com

stable inclusion from stable-v4.19.319 commit a561145f3ae973ebf3e0aee41624e92a6c5cb38d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGEF4 CVE: CVE-2024-41020

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit f8138f2ad2f745b9a1c696a05b749eabe44337ea upstream.

When I wrote commit 3cad1bc01041 ("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: c293621bbf67 ("[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-v1-1-1480967195... Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- fs/locks.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c index f4504008a2ea..6f27ec4f58da 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2661,8 +2661,9 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, error = do_lock_file_wait(filp, cmd, file_lock);

/* - * Attempt to detect a close/fcntl race and recover by releasing the - * lock that was just acquired. There is no need to do that when we're + * Detect close/fcntl races and recover by zapping all POSIX locks + * 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. */ if (!error && file_lock->fl_type != F_UNLCK && @@ -2676,9 +2677,7 @@ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, f = fcheck(fd); spin_unlock(&current->files->file_lock); if (f != filp) { - file_lock->fl_type = F_UNLCK; - error = do_lock_file_wait(filp, cmd, file_lock); - WARN_ON_ONCE(error); + locks_remove_posix(filp, &current->files); error = -EBADF; } }