On 12/21/2017 04:44 PM, John Snow wrote:
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 <js...@redhat.com>
---
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;
+ }
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
