Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932104Ab2KZRDY (ORCPT ); Mon, 26 Nov 2012 12:03:24 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47285 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756573Ab2KZRDU (ORCPT ); Mon, 26 Nov 2012 12:03:20 -0500 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Lukas Czerner , James Bottomley , Herton Ronaldo Krzesinski Subject: [PATCH 057/270] scsi_debug: Fix off-by-one bug when unmapping region Date: Mon, 26 Nov 2012 14:55:47 -0200 Message-Id: <1353949160-26803-58-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> References: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2183 Lines: 55 3.5.7u1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Czerner commit bc977749e967daa56de1922cf4cb38525631c51c upstream. Currently it is possible to unmap one more block than user requested to due to the off-by-one error in unmap_region(). This is probably due to the fact that the end variable despite its name actually points to the last block to unmap + 1. However in the condition it is handled as the last block of the region to unmap. The bug was not previously spotted probably due to the fact that the region was not zeroed, which has changed with commit be1dd78de5686c062bb3103f9e86d444a10ed783. With that commit we were able to corrupt the ext4 file system on 256M scsi_debug device with LBPRZ enabled using fstrim. Since the 'end' semantic is the same in several functions there this commit just fixes the condition to use the 'end' variable correctly in that context. Reported-by: Paolo Bonzini Signed-off-by: Lukas Czerner Reviewed-by: Martin K. Petersen Acked-by: Douglas Gilbert Signed-off-by: James Bottomley Signed-off-by: Herton Ronaldo Krzesinski --- drivers/scsi/scsi_debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c index 182d5a5..f4cc413 100644 --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -2054,7 +2054,7 @@ static void unmap_region(sector_t lba, unsigned int len) block = lba + alignment; rem = do_div(block, granularity); - if (rem == 0 && lba + granularity <= end && block < map_size) { + if (rem == 0 && lba + granularity < end && block < map_size) { clear_bit(block, map_storep); if (scsi_debug_lbprz) memset(fake_storep + -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/