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authorDavid Howells <dhowells@redhat.com>2022-08-17 19:41:27 +0100
committerJeff Layton <jlayton@kernel.org>2022-08-17 15:08:58 -0400
commit932c29a10d5d0bba63b9f505a8ec1e3ce8c02542 (patch)
treec892edb226d18424eb7637818b801944943937ce /fs/locks.c
parent274a2eebf80c60246f9edd6ef8e9a095ad121264 (diff)
locks: Fix dropped call to ->fl_release_private()
Prior to commit 4149be7bda7e, sys_flock() would allocate the file_lock struct it was going to use to pass parameters, call ->flock() and then call locks_free_lock() to get rid of it - which had the side effect of calling locks_release_private() and thus ->fl_release_private(). With commit 4149be7bda7e, however, this is no longer the case: the struct is now allocated on the stack, and locks_free_lock() is no longer called - and thus any remaining private data doesn't get cleaned up either. This causes afs flock to cause oops. Kasan catches this as a UAF by the list_del_init() in afs_fl_release_private() for the file_lock record produced by afs_fl_copy_lock() as the original record didn't get delisted. It can be reproduced using the generic/504 xfstest. Fix this by reinstating the locks_release_private() call in sys_flock(). I'm not sure if this would affect any other filesystems. If not, then the release could be done in afs_flock() instead. Changes ======= ver #2) - Don't need to call ->fl_release_private() after calling the security hook, only after calling ->flock(). Fixes: 4149be7bda7e ("fs/lock: Don't allocate file_lock in flock_make_lock().") cc: Chuck Lever <chuck.lever@oracle.com> cc: Jeff Layton <jlayton@kernel.org> cc: Marc Dionne <marc.dionne@auristor.com> cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/166075758809.3532462.13307935588777587536.stgit@warthog.procyon.org.uk/ # v1 Acked-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c
index c266cfdc3291..607f94a0e789 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2129,6 +2129,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
else
error = locks_lock_file_wait(f.file, &fl);
+ locks_release_private(&fl);
out_putf:
fdput(f);