This is a note to let you know that I've just added the patch titled
NFSD: Prevent NULL dereference in nfsd4_process_cb_update()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-prevent-null-dereference-in-nfsd4_process_cb_up.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b681176e2772e1af459d6987e8f2a612051b6e59
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu Oct 17 11:03:53 2024 -0400
NFSD: Prevent NULL dereference in nfsd4_process_cb_update()
[ Upstream commit 1e02c641c3a43c88cecc08402000418e15578d38 ]
@ses is initialized to NULL. If __nfsd4_find_backchannel() finds no
available backchannel session, setup_callback_client() will try to
dereference @ses and segfault.
Fixes: dcbeaa68dbbd ("nfsd4: allow backchannel recovery")
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index e6c7448d3d89a..8ca4c12dd22ec 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1134,6 +1134,8 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
ses = c->cn_session;
}
spin_unlock(&clp->cl_lock);
+ if (!c)
+ return;
err = setup_callback_client(clp, &conn, ses);
if (err) {
