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 42AD517730 for ; Mon, 15 May 2023 18:03:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96FD1C433B0; Mon, 15 May 2023 18:03:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173831; bh=xzd57sAhMJcCLY0Iw9hG3MNFGmdGOAnog91H/WQBI7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Vom7V/7eoBMsHgNiC5nfBORGW2Fo+kGqP3a8ggGv1iEarb+ws+dfVCUFF3h7pUaqR OMcgZIFg4RqEbuC8irPNSYYwsHBgICICCP3Y7amT7rUYlADKuBHmuQ7BfSFU8Qi+Un hRQGhAklBi71rZOiN/M2H9AWkLtqx+KS9l+Kan9Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhang Zhengming , Zhao Lei , Zhou Kete , Pengcheng Yang , Jens Axboe , Andrew Morton , Sasha Levin Subject: [PATCH 5.4 220/282] relayfs: fix out-of-bounds access in relay_file_read Date: Mon, 15 May 2023 18:29:58 +0200 Message-Id: <20230515161728.828830008@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161722.146344674@linuxfoundation.org> References: <20230515161722.146344674@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Zhang Zhengming [ Upstream commit 43ec16f1450f4936025a9bdf1a273affdb9732c1 ] There is a crash in relay_file_read, as the var from point to the end of last subbuf. The oops looks something like: pc : __arch_copy_to_user+0x180/0x310 lr : relay_file_read+0x20c/0x2c8 Call trace: __arch_copy_to_user+0x180/0x310 full_proxy_read+0x68/0x98 vfs_read+0xb0/0x1d0 ksys_read+0x6c/0xf0 __arm64_sys_read+0x20/0x28 el0_svc_common.constprop.3+0x84/0x108 do_el0_svc+0x74/0x90 el0_svc+0x1c/0x28 el0_sync_handler+0x88/0xb0 el0_sync+0x148/0x180 We get the condition by analyzing the vmcore: 1). The last produced byte and last consumed byte both at the end of the last subbuf 2). A softirq calls function(e.g __blk_add_trace) to write relay buffer occurs when an program is calling relay_file_read_avail(). relay_file_read relay_file_read_avail relay_file_read_consume(buf, 0, 0); //interrupted by softirq who will write subbuf .... return 1; //read_start point to the end of the last subbuf read_start = relay_file_read_start_pos //avail is equal to subsize avail = relay_file_read_subbuf_avail //from points to an invalid memory address from = buf->start + read_start //system is crashed copy_to_user(buffer, from, avail) Link: https://lkml.kernel.org/r/20230419040203.37676-1-zhang.zhengming@h3c.com Fixes: 8d62fdebdaf9 ("relay file read: start-pos fix") Signed-off-by: Zhang Zhengming Reviewed-by: Zhao Lei Reviewed-by: Zhou Kete Reviewed-by: Pengcheng Yang Cc: Jens Axboe Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/relay.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/relay.c b/kernel/relay.c index 989f78f16ad5c..1e11199c7d7cc 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -1077,7 +1077,8 @@ static size_t relay_file_read_start_pos(struct rchan_buf *buf) size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t consumed = buf->subbufs_consumed % n_subbufs; - size_t read_pos = consumed * subbuf_size + buf->bytes_consumed; + size_t read_pos = (consumed * subbuf_size + buf->bytes_consumed) + % (n_subbufs * subbuf_size); read_subbuf = read_pos / subbuf_size; padding = buf->padding[read_subbuf]; -- 2.39.2