From patchwork Thu Dec 13 22:04:15 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3/8] e2fsck/pass1.c: Fix undefined behavior in check_blocks() Date: Thu, 13 Dec 2012 12:04:15 -0000 From: Sami Liedes X-Patchwork-Id: 206259 Message-Id: <20121213220415.GK9713@sli.dy.fi> To: linux-ext4@vger.kernel.org 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;