Re: [Qemu-trivial] [PATCH 2/6] sheepdog: fix possible resouce leak and out-of-bounds access

[Gonglei (Arei)]

Regards,
-Gonglei


> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden
> Sent: Thursday, March 03, 2016 7:18 PM
> To: Gonglei (Arei); address@hidden
> Cc: address@hidden
> Subject: Re: [PATCH 2/6] sheepdog: fix possible resouce leak and out-of-bounds
> access
> 
> 
> 
> On 03/03/2016 10:43, Gonglei wrote:
> > CID 1352418 (#1 of 1): Out-of-bounds access (INCOMPATIBLE_CAST)
> > incompatible_cast: Pointer &snap_id points to an object whose effective
> > type is unsigned int (32 bits, unsigned) but is dereferenced as a wider
> > unsigned long (64 bits, unsigned). This may lead to memory corruption.
> >
> > We also need to free local_err when ret is not equals to 0.
> >
> > Signed-off-by: Gonglei <address@hidden>
> > ---
> >  block/sheepdog.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index 8739acc..3d81bba 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -2543,7 +2543,7 @@ static int sd_snapshot_delete(BlockDriverState
> *bs,
> >                                const char *name,
> >                                Error **errp)
> >  {
> > -    uint32_t snap_id = 0;
> > +    unsigned long snap_id = 0;
> >      char snap_tag[SD_MAX_VDI_TAG_LEN];
> >      Error *local_err = NULL;
> >      int fd, ret;
> > @@ -2565,20 +2565,23 @@ static int sd_snapshot_delete(BlockDriverState
> *bs,
> >      memset(buf, 0, sizeof(buf));
> >      memset(snap_tag, 0, sizeof(snap_tag));
> >      pstrcpy(buf, SD_MAX_VDI_LEN, s->name);
> > -    if (qemu_strtoul(snapshot_id, NULL, 10, (unsigned long *)&snap_id)) {
> > +    if (qemu_strtoul(snapshot_id, NULL, 10, &snap_id)) {
> >          return -1;
> >      }
> >
> >      if (snap_id) {
> > +        assert(snap_id <= UINT_MAX);
> > +
> >          hdr.snapid = snap_id;
> >      } else {
> >          pstrcpy(snap_tag, sizeof(snap_tag), snapshot_id);
> >          pstrcpy(buf + SD_MAX_VDI_LEN, SD_MAX_VDI_TAG_LEN,
> snap_tag);
> >      }
> >
> > -    ret = find_vdi_name(s, s->name, snap_id, snap_tag, &vid, true,
> > +    ret = find_vdi_name(s, s->name, hdr.snapid, snap_tag, &vid, true,
> >                          &local_err);
> >      if (ret) {
> > +        error_report_err(local_err);
> >          return ret;
> >      }
> >
> >
> 
> A patch for this has been posted yesterday by Jeff Cody.
> 

OK, I found it. And Max's comments is right, Jef can use hdr.snapid instead of 
snap_tag
to invoke find_vdi_name().

But, except that fix, My patch also fixed a memory leak, did you see that? Do I 
need
post an separate patch to fix memory leak?


Regards,
-Gonglei