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cifs: remove check of list iterator against head past the loop body

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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>
This commit is contained in:
Jakob Koschel 2022-03-31 23:55:41 +02:00 committed by Steve French
parent 687127c81a
commit 00c796eecb
1 changed files with 6 additions and 4 deletions
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10
fs/cifs/smb2misc.c
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@ -150,16 +150,18 @@ smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
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 == le64_to_cpu(thdr->SessionId))
list_for_each_entry(iter, &srvr->smb_ses_list, smb_ses_list) {
if (iter->Suid == le64_to_cpu(thdr->SessionId)) {
ses = iter;
break;
}
}
spin_unlock(&cifs_tcp_ses_lock);
if (list_entry_is_head(ses, &srvr->smb_ses_list,
smb_ses_list)) {
if (!ses) {
cifs_dbg(VFS, "no decryption - session id not found\n");
return 1;
}