[PATCH 4.19 102/168] Smack: fix another vsscanf out of bounds

Greg Kroah-Hartman
2020-08-17T17:40:59Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit a6bd4f6d9b07452b0b19842044a6c3ea384b0b88 ]

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: Sasha Levin <sashal@kernel.org>
---
security/smack/smackfs.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 10ee51d044926..981f582539acf 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -933,6 +933,10 @@ 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;
--
2.25.1