From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sami Liedes Subject: [PATCH 3/8] e2fsck/pass1.c: Fix undefined behavior in check_blocks() Date: Fri, 14 Dec 2012 00:04:15 +0200 Message-ID: <20121213220415.GK9713@sli.dy.fi> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-ext4@vger.kernel.org Return-path: Received: from smtp-2.hut.fi ([130.233.228.92]:33955 "EHLO smtp-2.hut.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754985Ab2LMWiy (ORCPT ); Thu, 13 Dec 2012 17:38:54 -0500 Received: from localhost (katosiko.hut.fi [130.233.228.115]) by smtp-2.hut.fi (8.13.6/8.12.10) with ESMTP id qBDM4OGS004484 for ; Fri, 14 Dec 2012 00:04:24 +0200 Received: from smtp-2.hut.fi ([130.233.228.92]) by localhost (katosiko.hut.fi [130.233.228.115]) (amavisd-new, port 10024) with LMTP id 09545-141 for ; Fri, 14 Dec 2012 00:04:24 +0200 (EET) Received: from kosh.localdomain (kosh.hut.fi [130.233.228.12]) by smtp-2.hut.fi (8.13.6/8.12.10) with ESMTP id qBDM4Frh004477 for ; Fri, 14 Dec 2012 00:04:15 +0200 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: The offending code is this: pb.max_blocks = 1 << (31 - fs->super->s_log_block_size); While pb.max_blocks is of type blk64_t, the intermediate result of the expression '1 << 31' is int. However 1 << 31 does not fit in a 32-bit signed int, causing undefined behavior. Caught using clang -fsanitize=undefined. Signed-off-by: Sami Liedes --- e2fsck/pass1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c index a4bd956..9cd8832 100644 --- a/e2fsck/pass1.c +++ b/e2fsck/pass1.c @@ -2095,7 +2095,7 @@ static void check_blocks(e2fsck_t ctx, struct problem_context *pctx, pb.previous_block = 0; pb.is_dir = LINUX_S_ISDIR(inode->i_mode); pb.is_reg = LINUX_S_ISREG(inode->i_mode); - pb.max_blocks = 1 << (31 - fs->super->s_log_block_size); + pb.max_blocks = ((blk64_t)1) << (31 - fs->super->s_log_block_size); pb.inode = inode; pb.pctx = pctx; pb.ctx = ctx; -- 1.7.10.4