From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A867B641; Tue, 16 Jul 2024 15:41:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721144462; cv=none; b=dBEF/9Pbn65/+ZjRlgaAs27svLGSUsSa/vkvr2s32Tn6JecKCdTwXnaWUB+nQyJu4hJFhThfZFMhB47teEmDbpROxLBnW5tmeIcrNYvoFD3KxS88ouVlaBcKhtNbSOcq33jGLs+zHs99ZwlvE2JA9wXbFa5onGmfwH5pp1q+LQk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721144462; c=relaxed/simple; bh=qQrfzvZBB43qGL/KT6ZWTfuPIjmY4ksiocp63WSMgGs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tjdq1zlpPmFgF5XsqnmTj4S4Z2Pn6WtHJq2XxBdkujecIDU7S6efo+J8EptHb9X2ngiicq7u7/xRHF/Jxd6gDH83lcMDV/Mz1L9LkxFKRmuV3S9DZCAyRRfvWZc8Ke+yPsjnQgRj6oy7+cA3t/uzRjJO4BY/v9+B4m3FKlmwYvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AREUMtcg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AREUMtcg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA189C116B1; Tue, 16 Jul 2024 15:41:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1721144462; bh=qQrfzvZBB43qGL/KT6ZWTfuPIjmY4ksiocp63WSMgGs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AREUMtcggqAJussCcaxmb2xJqTAUeQ2K3zOivkTHU0b1Z6DNgxwcLjHo7ftqcrl9Z i3S7Q9tlHB5cicmcNUmnnewiJkzD/ax9dkk1amap8gbK+thA4CBcY7p+c4YuEWiLaU thGhovAfg6ph4qPBvIVRHLGW0k6T49QAxBQ7oR5E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+ec0723ba9605678b14bf@syzkaller.appspotmail.com, Dmitry Antipov , Paolo Abeni , Sasha Levin Subject: [PATCH 5.4 54/78] ppp: reject claimed-as-LCP but actually malformed packets Date: Tue, 16 Jul 2024 17:31:26 +0200 Message-ID: <20240716152742.732360887@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240716152740.626160410@linuxfoundation.org> References: <20240716152740.626160410@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Antipov [ Upstream commit f2aeb7306a898e1cbd03963d376f4b6656ca2b55 ] Since 'ppp_async_encode()' assumes valid LCP packets (with code from 1 to 7 inclusive), add 'ppp_check_packet()' to ensure that LCP packet has an actual body beyond PPP_LCP header bytes, and reject claimed-as-LCP but actually malformed data otherwise. Reported-by: syzbot+ec0723ba9605678b14bf@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ec0723ba9605678b14bf Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Dmitry Antipov Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- drivers/net/ppp/ppp_generic.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 078c0f474f966..3cd4196b36b21 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -70,6 +70,7 @@ #define MPHDRLEN_SSN 4 /* ditto with short sequence numbers */ #define PPP_PROTO_LEN 2 +#define PPP_LCP_HDRLEN 4 /* * An instance of /dev/ppp can be associated with either a ppp @@ -491,6 +492,15 @@ static ssize_t ppp_read(struct file *file, char __user *buf, return ret; } +static bool ppp_check_packet(struct sk_buff *skb, size_t count) +{ + /* LCP packets must include LCP header which 4 bytes long: + * 1-byte code, 1-byte identifier, and 2-byte length. + */ + return get_unaligned_be16(skb->data) != PPP_LCP || + count >= PPP_PROTO_LEN + PPP_LCP_HDRLEN; +} + static ssize_t ppp_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { @@ -513,6 +523,11 @@ static ssize_t ppp_write(struct file *file, const char __user *buf, kfree_skb(skb); goto out; } + ret = -EINVAL; + if (unlikely(!ppp_check_packet(skb, count))) { + kfree_skb(skb); + goto out; + } switch (pf->kind) { case INTERFACE: -- 2.43.0