Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964933Ab2JSDC2 (ORCPT ); Thu, 18 Oct 2012 23:02:28 -0400 Received: from mail.kernel.org ([198.145.19.201]:52157 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964903Ab2JSCsw (ORCPT ); Thu, 18 Oct 2012 22:48:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Paolo Bonzini , Lukas Czerner , "Martin K. Petersen" , Douglas Gilbert , James Bottomley Subject: [ 23/76] SCSI: scsi_debug: Fix off-by-one bug when unmapping region Date: Thu, 18 Oct 2012 19:46:47 -0700 Message-Id: <20121019024353.832966031@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121019024350.087156547@linuxfoundation.org> References: <20121019024350.087156547@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2043 Lines: 53 3.6-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: Greg Kroah-Hartman --- drivers/scsi/scsi_debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -2054,7 +2054,7 @@ static void unmap_region(sector_t lba, u 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 + -- 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/