| Message ID | 1396275242-10810-13-git-send-email-mst@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 31 March 2014 15:16, Michael S. Tsirkin <mst@redhat.com> wrote: > CVE-2013-4531 > > cpreg_vmstate_indexes is a VARRAY_INT32. A negative value for > cpreg_vmstate_array_len will cause a buffer overflow. > > VMSTATE_INT32_LE was supposed to protect against this > but doesn't because it doesn't validate that input is > non-negative. > > Fix this macro to valide the value appropriately. > > The only other user of VMSTATE_INT32_LE doesn't > ever use negative numbers so it doesn't care. This fixes the bug, but it's rather unintuitive semantics for an INT32_LE not to simply do a signed comparison... Maybe rename the macro? thanks -- PMM
On Mon, Mar 31, 2014 at 04:40:41PM +0100, Peter Maydell wrote: > On 31 March 2014 15:16, Michael S. Tsirkin <mst@redhat.com> wrote: > > CVE-2013-4531 > > > > cpreg_vmstate_indexes is a VARRAY_INT32. A negative value for > > cpreg_vmstate_array_len will cause a buffer overflow. > > > > VMSTATE_INT32_LE was supposed to protect against this > > but doesn't because it doesn't validate that input is > > non-negative. > > > > Fix this macro to valide the value appropriately. > > > > The only other user of VMSTATE_INT32_LE doesn't > > ever use negative numbers so it doesn't care. > > This fixes the bug, but it's rather unintuitive semantics > for an INT32_LE not to simply do a signed comparison... > Maybe rename the macro? > > thanks > -- PMM Sure. I'll do it in a separate patch though.
diff --git a/vmstate.c b/vmstate.c index 02d5d94..e1e9cae 100644 --- a/vmstate.c +++ b/vmstate.c @@ -340,8 +340,9 @@ const VMStateInfo vmstate_info_int32_equal = { .put = put_int32, }; -/* 32 bit int. Check that the received value is less than or equal to - the one in the field */ +/* 32 bit int. Check that the received value is non-negative + * and less than or equal to the one in the field. + */ static int get_int32_le(QEMUFile *f, void *pv, size_t size) { @@ -349,7 +350,7 @@ static int get_int32_le(QEMUFile *f, void *pv, size_t size) int32_t loaded; qemu_get_sbe32s(f, &loaded); - if (loaded <= *cur) { + if (loaded >= 0 && loaded <= *cur) { *cur = loaded; return 0; }
CVE-2013-4531 cpreg_vmstate_indexes is a VARRAY_INT32. A negative value for cpreg_vmstate_array_len will cause a buffer overflow. VMSTATE_INT32_LE was supposed to protect against this but doesn't because it doesn't validate that input is non-negative. Fix this macro to valide the value appropriately. The only other user of VMSTATE_INT32_LE doesn't ever use negative numbers so it doesn't care. Reported-by: Anthony Liguori <anthony@codemonkey.ws> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- vmstate.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)