On 08/09/12 10:52, Dan Carpenter wrote: > If m.num is too large then the "m.num * sizeof(*m.arr)" multiplication > could overflow and the access_ok() check wouldn't test the right size.
m.num is range checked later on so it doesn't matter that the access_ok() checks might be wrong. A bit subtle, perhaps. David > Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com> > --- > Only needed in linux-next. > > diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c > index 215a3c0..fdff8f9 100644 > --- a/drivers/xen/privcmd.c > +++ b/drivers/xen/privcmd.c > @@ -325,6 +325,8 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, > int version) > return -EFAULT; > /* Returns per-frame error in m.arr. */ > m.err = NULL; > + if (m.num > SIZE_MAX / sizeof(*m.arr)) > + return -EINVAL; > if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr))) > return -EFAULT; > break; > @@ -332,6 +334,8 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, > int version) > if (copy_from_user(&m, udata, sizeof(struct > privcmd_mmapbatch_v2))) > return -EFAULT; > /* Returns per-frame error code in m.err. */ > + if (m.num > SIZE_MAX / sizeof(*m.err)) > + return -EINVAL; > if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err)))) > return -EFAULT; > break; > > _______________________________________________ > Xen-devel mailing list > xen-de...@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
