From 59ac1aac1550731ca241007af660fc5278c88136 Mon Sep 17 00:00:00 2001 From: Su Hui Date: Thu, 8 Aug 2024 20:23:32 +0800 Subject: [PATCH] smb/client: avoid possible NULL dereference in cifs_free_subrequest() Clang static checker (scan-build) warning: cifsglob.h:line 890, column 3 Access to field 'ops' results in a dereference of a null pointer. Commit 519be989717c ("cifs: Add a tracepoint to track credits involved in R/W requests") adds a check for 'rdata->server', and let clang throw this warning about NULL dereference. When 'rdata->credits.value != 0 && rdata->server == NULL' happens, add_credits_and_wake_if() will call rdata->server->ops->add_credits(). This will cause NULL dereference problem. Add a check for 'rdata->server' to avoid NULL dereference. Cc: stable@vger.kernel.org Fixes: 69c3c023af25 ("cifs: Implement netfslib hooks") Cc: David Howells Signed-off-by: Su Hui Signed-off-by: Steve French --- fs/smb/client/file.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c index b2405dd4d4d4..45459af5044d 100644 --- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -315,7 +315,7 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq) #endif } - if (rdata->credits.value != 0) + if (rdata->credits.value != 0) { trace_smb3_rw_credits(rdata->rreq->debug_id, rdata->subreq.debug_index, rdata->credits.value, @@ -323,8 +323,12 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq) rdata->server ? rdata->server->in_flight : 0, -rdata->credits.value, cifs_trace_rw_credits_free_subreq); + if (rdata->server) + add_credits_and_wake_if(rdata->server, &rdata->credits, 0); + else + rdata->credits.value = 0; + } - add_credits_and_wake_if(rdata->server, &rdata->credits, 0); if (rdata->have_xid) free_xid(rdata->xid); } -- 2.43.0