From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvRokAMslgZ5HtKI5HCnHuAAWnwfZ+DO6l+YrvvqfWMDLNQM2JyYwOG58MZe2lhpUByED3H ARC-Seal: i=1; a=rsa-sha256; t=1520451678; cv=none; d=google.com; s=arc-20160816; b=aRR6syaHKQERQ5TO/dAgCueU1Qzkd3aQ9NYKanbG8OYlpzNN20tkm5LNqvBOKkyNgI 0iOePqQIavB1PwTVsYiEVeUdgjyo0X8dzulVAech/IaBSJWZR3lkYaD3rmBg9fhuktKl ErxADm0+ofKdyW93q9XXmEzIWHtRdY16017mvllftkcvNQRiFHYm4MMPPNxTk7Nc+Is5 DOR5ouVWNdRaHq0YKQEFZ5AxzvmJldXZfPNPS8KzsCAvey6oUwOgxiokQdzKQDHiLnOn Z/BVxuxEtkStfVEZNYntq1hFIAS4WXrE9ADySAcGzYp9M/BP6770bg+mlG8yRuVw/T93 Kwcw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=HL/ZSKOaEdFq5tegvmW7upXgwCZ7bjrm443GsTB2ADc=; b=CsjAllIBQmVaX8n3V/e80utIo6kDkxo86/SlExs+PYfsAPsztRr754anRLYwSQOPag 5fbb4zis0TT41HZQGhPvmx16Fx1yqRtJSx5iHsvOjUqR72ayOQ2nSzOMt3PsGHlaJ1AJ evL0caEZ9MtvffQVc5UjHWaBjnHH/tQ1VH2CC9hs8RLemhhmQp2LobCryk2RGc6ar+Ps q6IOZy5SEO09fKV6z8WpIQyeQxvbPjKF6BesUshl3JLm5kuZS0SU7TqY13Whw6ptKkEg bSRwKwKHQGIO4isM0gfKCyrpQEiBc2WVyEKfoPY4MrAX8eNqy/udXddSROLwniZZ0xl0 e29g== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Kodanev , Marcelo Ricardo Leitner , Neil Horman , "David S. Miller" Subject: [PATCH 4.15 050/122] sctp: verify size of a new chunk in _sctp_make_chunk() Date: Wed, 7 Mar 2018 11:37:42 -0800 Message-Id: <20180307191736.274951227@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180307191729.190879024@linuxfoundation.org> References: <20180307191729.190879024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594309139344235247?= X-GMAIL-MSGID: =?utf-8?q?1594309139344235247?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexey Kodanev [ Upstream commit 07f2c7ab6f8d0a7e7c5764c4e6cc9c52951b9d9c ] When SCTP makes INIT or INIT_ACK packet the total chunk length can exceed SCTP_MAX_CHUNK_LEN which leads to kernel panic when transmitting these packets, e.g. the crash on sending INIT_ACK: [ 597.804948] skbuff: skb_over_panic: text:00000000ffae06e4 len:120168 put:120156 head:000000007aa47635 data:00000000d991c2de tail:0x1d640 end:0xfec0 dev: ... [ 597.976970] ------------[ cut here ]------------ [ 598.033408] kernel BUG at net/core/skbuff.c:104! [ 600.314841] Call Trace: [ 600.345829] [ 600.371639] ? sctp_packet_transmit+0x2095/0x26d0 [sctp] [ 600.436934] skb_put+0x16c/0x200 [ 600.477295] sctp_packet_transmit+0x2095/0x26d0 [sctp] [ 600.540630] ? sctp_packet_config+0x890/0x890 [sctp] [ 600.601781] ? __sctp_packet_append_chunk+0x3b4/0xd00 [sctp] [ 600.671356] ? sctp_cmp_addr_exact+0x3f/0x90 [sctp] [ 600.731482] sctp_outq_flush+0x663/0x30d0 [sctp] [ 600.788565] ? sctp_make_init+0xbf0/0xbf0 [sctp] [ 600.845555] ? sctp_check_transmitted+0x18f0/0x18f0 [sctp] [ 600.912945] ? sctp_outq_tail+0x631/0x9d0 [sctp] [ 600.969936] sctp_cmd_interpreter.isra.22+0x3be1/0x5cb0 [sctp] [ 601.041593] ? sctp_sf_do_5_1B_init+0x85f/0xc30 [sctp] [ 601.104837] ? sctp_generate_t1_cookie_event+0x20/0x20 [sctp] [ 601.175436] ? sctp_eat_data+0x1710/0x1710 [sctp] [ 601.233575] sctp_do_sm+0x182/0x560 [sctp] [ 601.284328] ? sctp_has_association+0x70/0x70 [sctp] [ 601.345586] ? sctp_rcv+0xef4/0x32f0 [sctp] [ 601.397478] ? sctp6_rcv+0xa/0x20 [sctp] ... Here the chunk size for INIT_ACK packet becomes too big, mostly because of the state cookie (INIT packet has large size with many address parameters), plus additional server parameters. Later this chunk causes the panic in skb_put_data(): skb_packet_transmit() sctp_packet_pack() skb_put_data(nskb, chunk->skb->data, chunk->skb->len); 'nskb' (head skb) was previously allocated with packet->size from u16 'chunk->chunk_hdr->length'. As suggested by Marcelo we should check the chunk's length in _sctp_make_chunk() before trying to allocate skb for it and discard a chunk if its size bigger than SCTP_MAX_CHUNK_LEN. Signed-off-by: Alexey Kodanev Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/sm_make_chunk.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -1378,9 +1378,14 @@ static struct sctp_chunk *_sctp_make_chu struct sctp_chunk *retval; struct sk_buff *skb; struct sock *sk; + int chunklen; + + chunklen = SCTP_PAD4(sizeof(*chunk_hdr) + paylen); + if (chunklen > SCTP_MAX_CHUNK_LEN) + goto nodata; /* No need to allocate LL here, as this is only a chunk. */ - skb = alloc_skb(SCTP_PAD4(sizeof(*chunk_hdr) + paylen), gfp); + skb = alloc_skb(chunklen, gfp); if (!skb) goto nodata;