I made a mistake on the fixes line, it should have been

Fixes: 06d57378bcc9 ("cifs: Fix potential deadlock when updating vol in cifs_reconnect()")

-       if (!IS_ERR(vi)) -               free_vol(vi); -       mutex_unlock(&vol_lock); +       spin_unlock(&vol_list_lock); + +       kref_put(&vi->refcnt, vol_release);

This change is not needed for 5.4 unless the deadlock change is also needed.

Tom

On 1/17/21 6:16 AM, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 77b6ec01c29aade01701aa30bf1469acc7f2be76 Mon Sep 17 00:00:00 2001 From: Tom Rix trix@redhat.com Date: Tue, 5 Jan 2021 12:21:26 -0800 Subject: [PATCH] cifs: check pointer before freeing

clang static analysis reports this problem

dfs_cache.c:591:2: warning: Argument to kfree() is a constant address (18446744073709551614), which is not memory allocated by malloc() kfree(vi); ^~~~~~~~~

In dfs_cache_del_vol() the volume info pointer 'vi' being freed is the return of a call to find_vol(). The large constant address is find_vol() returning an error.

Add an error check to dfs_cache_del_vol() similar to the one done in dfs_cache_update_vol().

Fixes: 54be1f6c1c37 ("cifs: Add DFS cache routines") Signed-off-by: Tom Rix trix@redhat.com Reviewed-by: Nathan Chancellor natechancellor@gmail.com CC: stable@vger.kernel.org # v5.0+ Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c index 6ad6ba5f6ebe..0fdb0de7ff86 100644 --- a/fs/cifs/dfs_cache.c +++ b/fs/cifs/dfs_cache.c @@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath) vi = find_vol(fullpath); spin_unlock(&vol_list_lock);

• kref_put(&vi->refcnt, vol_release);

• if (!IS_ERR(vi))

• kref_put(&vi->refcnt, vol_release);
  

} /**