From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50181) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eS9Zc-0005DQ-Uy for qemu-devel@nongnu.org; Thu, 21 Dec 2017 17:44:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eS9Zb-0004kb-VZ for qemu-devel@nongnu.org; Thu, 21 Dec 2017 17:44:21 -0500 From: John Snow Date: Thu, 21 Dec 2017 17:44:11 -0500 Message-Id: <20171221224411.8901-1-jsnow@redhat.com> Subject: [Qemu-devel] [PATCH] file-posix: refuse to open directories List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org, dgilbert@redhat.com, mreitz@redhat.com, John Snow I don't think there's a legitimate reason to open directories as if they were files. This prevents QEMU from opening and attempting to probe a directory inode, which can break in exciting ways. One of those ways is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file size instead of EISDIR. This can coax QEMU into responding with a confusing "file too big" instead of "Hey, that's not a file". See: https://bugs.launchpad.net/qemu/+bug/1739304/ Signed-off-by: John Snow --- block/file-posix.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/file-posix.c b/block/file-posix.c index 36ee89e940..bd29bdada6 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -589,6 +589,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, s->needs_alignment = true; } #endif + if (S_ISDIR(st.st_mode)) { + ret = -EISDIR; + error_setg_errno(errp, errno, "Cannot open directory as file"); + goto fail; + } #ifdef CONFIG_XFS if (platform_test_xfs_fd(s->fd)) { -- 2.14.3