From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755542Ab2GaEu6 (ORCPT ); Tue, 31 Jul 2012 00:50:58 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:48780 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755634Ab2GaEuy (ORCPT ); Tue, 31 Jul 2012 00:50:54 -0400 Message-Id: <20120731044318.518249620@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Tue, 31 Jul 2012 05:43:55 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Roland Dreier , Nicholas Bellinger Subject: [ 45/73] target: Fix possible integer underflow in UNMAP emulation In-Reply-To: <20120731044310.013763753@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Roland Dreier commit b7fc7f3777582dea85156a821d78a522a0c083aa upstream. It's possible for an initiator to send us an UNMAP command with a descriptor that is less than 8 bytes; in that case it's really bad for us to set an unsigned int to that value, subtract 8 from it, and then use that as a limit for our loop (since the value will wrap around to a huge positive value). Fix this by making size be signed and only looping if size >= 16 (ie if we have at least a full descriptor available). Also remove offset as an obfuscated name for the constant 8. Signed-off-by: Roland Dreier Signed-off-by: Nicholas Bellinger [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/target/target_core_cdb.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) --- a/drivers/target/target_core_cdb.c +++ b/drivers/target/target_core_cdb.c @@ -1115,9 +1115,10 @@ int target_emulate_unmap(struct se_task struct se_device *dev = cmd->se_dev; unsigned char *buf, *ptr = NULL; sector_t lba; - unsigned int size = cmd->data_length, range; - int ret = 0, offset; - unsigned short dl, bd_dl; + int size = cmd->data_length; + u32 range; + int ret = 0; + int dl, bd_dl; if (!dev->transport->do_discard) { pr_err("UNMAP emulation not supported for: %s\n", @@ -1126,20 +1127,19 @@ int target_emulate_unmap(struct se_task return -ENOSYS; } - /* First UNMAP block descriptor starts at 8 byte offset */ - offset = 8; - size -= 8; - buf = transport_kmap_data_sg(cmd); dl = get_unaligned_be16(&buf[0]); bd_dl = get_unaligned_be16(&buf[2]); - ptr = &buf[offset]; - pr_debug("UNMAP: Sub: %s Using dl: %hu bd_dl: %hu size: %hu" + size = min(size - 8, bd_dl); + + /* First UNMAP block descriptor starts at 8 byte offset */ + ptr = &buf[8]; + pr_debug("UNMAP: Sub: %s Using dl: %u bd_dl: %u size: %u" " ptr: %p\n", dev->transport->name, dl, bd_dl, size, ptr); - while (size) { + while (size >= 16) { lba = get_unaligned_be64(&ptr[0]); range = get_unaligned_be32(&ptr[8]); pr_debug("UNMAP: Using lba: %llu and range: %u\n",