On Wed, Jun 23, 2021 at 08:00:21PM +0200, Philippe Mathieu-Daudé wrote: > In commit a9bcedd15a5 ("hw/sd/sdcard: Do not allow invalid SD card > sizes") we tried to protect us from CVE-2020-13253 by only allowing > card with power-of-2 sizes. However doing so we disrupted valid user > cases. As a compromise, allow any card size, but warn only power of 2 > sizes are supported, still suggesting the user how to increase a > card with 'qemu-img resize'. > > Cc: Tom Yan <tom.t...@gmail.com> > Cc: Warner Losh <i...@bsdimp.com> > Buglink: https://bugs.launchpad.net/qemu/+bug/1910586 > Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> > --- > hw/sd/sd.c | 25 +++++++++---------------- > 1 file changed, 9 insertions(+), 16 deletions(-) > > diff --git a/hw/sd/sd.c b/hw/sd/sd.c > index 9c8dd11bad1..cab4aab1475 100644 > --- a/hw/sd/sd.c > +++ b/hw/sd/sd.c > @@ -2131,23 +2131,16 @@ static void sd_realize(DeviceState *dev, Error **errp) > blk_size = blk_getlength(sd->blk); > if (blk_size > 0 && !is_power_of_2(blk_size)) { > int64_t blk_size_aligned = pow2ceil(blk_size); > - char *blk_size_str; > + g_autofree char *blk_size_s = size_to_str(blk_size); > + g_autofree char *blk_size_aligned_s = > size_to_str(blk_size_aligned); > > - blk_size_str = size_to_str(blk_size); > - error_setg(errp, "Invalid SD card size: %s", blk_size_str); > - g_free(blk_size_str); > - > - blk_size_str = size_to_str(blk_size_aligned); > - error_append_hint(errp, > - "SD card size has to be a power of 2, e.g. > %s.\n" > - "You can resize disk images with" > - " 'qemu-img resize <imagefile> <new-size>'\n" > - "(note that this will lose data if you make > the" > - " image smaller than it currently is).\n", > - blk_size_str); > - g_free(blk_size_str); > - > - return; > + warn_report("SD card size is not a power of 2 (%s). It might > work" > + " but is not supported by QEMU. If possible, resize" > + " your disk image to %s with:", > + blk_size_s, blk_size_aligned_s); > + warn_report(" 'qemu-img resize <imagefile> <new-size>'"); > + warn_report("(note that this will lose data if you make the" > + " image smaller than it currently is).");
In what scenarios will non-power of 2 not work and what is the effect ? Is it a QEMU bug or not ? 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 :|