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From: Florian Westphal <fw@strlen.de>
To: <netfilter-devel@vger.kernel.org>
Cc: <netdev@vger.kernel.org>,
	torvalds@linux-foundation.org, syzkaller-bugs@googlegroups.com,
	Florian Westphal <fw@strlen.de>,
	syzbot+e86f7c428c8c50db65b4@syzkaller.appspotmail.com
Subject: [PATCH nf] netfilter: xt_RATEEST: reject non-null terminated string from userspace
Date: Tue, 22 Dec 2020 23:23:56 +0100	[thread overview]
Message-ID: <20201222222356.22645-1-fw@strlen.de> (raw)
In-Reply-To: <000000000000fcbe0705b70e9bd9@google.com>

syzbot reports:
detected buffer overflow in strlen
[..]
Call Trace:
 strlen include/linux/string.h:325 [inline]
 strlcpy include/linux/string.h:348 [inline]
 xt_rateest_tg_checkentry+0x2a5/0x6b0 net/netfilter/xt_RATEEST.c:143

strlcpy assumes src is a c-string. Check info->name before its used.

Reported-by: syzbot+e86f7c428c8c50db65b4@syzkaller.appspotmail.com
Fixes: 5859034d7eb8793 ("[NETFILTER]: x_tables: add RATEEST target")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
RATEEST test in iptables.git still passes, syzbot repro setsockopt
fails with -ENAMETOOLONG.

diff --git a/net/netfilter/xt_RATEEST.c b/net/netfilter/xt_RATEEST.c
index 37253d399c6b..0d5c422f8745 100644
--- a/net/netfilter/xt_RATEEST.c
+++ b/net/netfilter/xt_RATEEST.c
@@ -115,6 +115,9 @@ static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 	} cfg;
 	int ret;
 
+	if (strnlen(info->name, sizeof(est->name)) >= sizeof(est->name))
+		return -ENAMETOOLONG;
+
 	net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
 
 	mutex_lock(&xn->hash_lock);
-- 
2.26.2


  parent reply	other threads:[~2020-12-22 22:25 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-22 14:44 kernel BUG at lib/string.c:LINE! (6) syzbot
2020-12-22 22:01 ` Linus Torvalds
2020-12-22 22:07   ` Florian Westphal
2020-12-23 11:25     ` Dmitry Vyukov
2020-12-22 22:23 ` Florian Westphal [this message]
2020-12-22 22:29   ` [PATCH nf] netfilter: xt_RATEEST: reject non-null terminated string from userspace Linus Torvalds
2020-12-22 22:50     ` Florian Westphal
2020-12-27 10:53   ` Pablo Neira Ayuso

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