From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F336C2B9F4 for ; Fri, 25 Jun 2021 16:05:03 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id A4E8E6196E for ; Fri, 25 Jun 2021 16:05:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A4E8E6196E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=windriver.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-21323-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 7901 invoked by uid 550); 25 Jun 2021 16:04:46 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 7833 invoked from network); 25 Jun 2021 16:04:45 -0000 From: Yun Zhou To: CC: , , , Subject: [PATCH 1/2] seq_buf: fix overflow when length is bigger than 8 Date: Fri, 25 Jun 2021 23:53:47 +0800 Message-ID: <20210625155348.58266-1-yun.zhou@windriver.com> X-Mailer: git-send-email 2.26.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain There's two variables being increased in that loop (i and j), and i follows the raw data, and j follows what is being written into the buffer. We should compare 'i' to MAX_MEMHEX_BYTES or compare 'j' to HEX_CHARS. Otherwise, if 'j' goes bigger than HEX_CHARS, it will overflow the destination buffer. This bug was introduced by commit 6d2289f3faa71dcc ("tracing: Make trace_seq_putmem_hex() more robust") Signed-off-by: Yun Zhou --- lib/seq_buf.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-) diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 6aabb609dd87..aa2f666e584e 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -210,7 +210,8 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len) * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex * @s: seq_buf descriptor * @mem: The raw memory to write its hex ASCII representation of - * @len: The length of the raw memory to copy (in bytes) + * @len: The length of the raw memory to copy (in bytes). + * It can be not larger than 8. * * This is similar to seq_buf_putmem() except instead of just copying the * raw memory into the buffer it writes its ASCII representation of it @@ -228,27 +229,19 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem, WARN_ON(s->size == 0); - while (len) { - start_len = min(len, HEX_CHARS - 1); + start_len = min(len, MAX_MEMHEX_BYTES); #ifdef __BIG_ENDIAN - for (i = 0, j = 0; i < start_len; i++) { + for (i = 0, j = 0; i < start_len; i++) { #else - for (i = start_len-1, j = 0; i >= 0; i--) { + for (i = start_len-1, j = 0; i >= 0; i--) { #endif - hex[j++] = hex_asc_hi(data[i]); - hex[j++] = hex_asc_lo(data[i]); - } - if (WARN_ON_ONCE(j == 0 || j/2 > len)) - break; - - /* j increments twice per loop */ - len -= j / 2; - hex[j++] = ' '; - - seq_buf_putmem(s, hex, j); - if (seq_buf_has_overflowed(s)) - return -1; + hex[j++] = hex_asc_hi(data[i]); + hex[j++] = hex_asc_lo(data[i]); } + + seq_buf_putmem(s, hex, j); + if (seq_buf_has_overflowed(s)) + return -1; return 0; } -- 2.26.1