On Thu, Dec 21, 2017 at 05:44:11PM -0500, 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; > + }
Should we also do the same for S_ISCHR & S_ISFIFO, because neither of them allow seeking, which IIUC would prevent usage in the file driver for random I/O. It would be fine todo that in a followup patch though, so from this patch pov Reviewed-by: Daniel P. Berrange <berra...@redhat.com> Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
