From: Jakob Koschel <jakobkoschel@gmail.com>
Date: Thu, 31 Mar 2022 23:55:41 +0200
Subject: [PATCH] cifs: remove check of list iterator against head past the
loop body
Git-commit: 00c796eecba4898194ea549679797ee28f89a92f
References: bsc#1190317
Patch-mainline: v5.18-rc2
When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.
While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.
In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
fs/cifs/smb2misc.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -163,15 +163,18 @@ smb2_check_message(char *buf, unsigned i
struct smb2_transform_hdr *thdr =
(struct smb2_transform_hdr *)buf;
struct cifs_ses *ses = NULL;
+ struct cifs_ses *iter;
/* decrypt frame now that it is completely read in */
spin_lock(&cifs_tcp_ses_lock);
- list_for_each_entry(ses, &srvr->smb_ses_list, smb_ses_list) {
- if (ses->Suid == thdr->SessionId)
+ list_for_each_entry(iter, &srvr->smb_ses_list, smb_ses_list) {
+ if (iter->Suid == thdr->SessionId) {
+ ses = iter;
break;
+ }
}
spin_unlock(&cifs_tcp_ses_lock);
- if (&ses->smb_ses_list == &srvr->smb_ses_list) {
+ if (!ses) {
cifs_dbg(VFS, "no decryption - session id not found\n");
return 1;
}