release/5.2.59/Smack-fix-another-vsscanf-out-of-bounds.patch

From 6cc967311d9ebfafacb40536a47547d4f18f0e26 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 23 Jul 2020 18:22:19 +0300
Subject: [PATCH] Smack: fix another vsscanf out of bounds

commit a6bd4f6d9b07452b0b19842044a6c3ea384b0b88 upstream.

This is similar to commit 84e99e58e8d1 ("Smack: slab-out-of-bounds in
vsscanf") where we added a bounds check on "rule".

Reported-by: syzbot+a22c6092d003d6fe1122@syzkaller.appspotmail.com
Fixes: f7112e6c9abf ("Smack: allow for significantly longer Smack labels v4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 5ff9e65cf253..fd6207473fd4 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -904,6 +904,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
 
 	for (i = 0; i < catlen; i++) {
 		rule += SMK_DIGITLEN;
+		if (rule > data + count) {
+			rc = -EOVERFLOW;
+			goto out;
+		}
 		ret = sscanf(rule, "%u", &cat);
 		if (ret != 1 || cat > SMACK_CIPSO_MAXCATNUM)
 			goto out;
-- 
2.27.0