On Mon, Sep 16, 2024 at 06:14:47PM +0300, Dan Carpenter wrote:
> Hello Chuck Lever,
>
> Commit 78147ca8b4a9 ("svcrdma: Add a "parsed chunk list" data
> structure") from Jun 22, 2020 (linux-next), leads to the following
> Smatch static checker warning:
>
> net/sunrpc/xprtrdma/svc_rdma_recvfrom.c:498 xdr_check_write_chunk()
> warn: potential user controlled sizeof overflow 'segcount * 4 * 4'
>
> net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> 488 static bool xdr_check_write_chunk(struct svc_rdma_recv_ctxt *rctxt)
> 489 {
> 490 u32 segcount;
> 491 __be32 *p;
> 492
> 493 if (xdr_stream_decode_u32(&rctxt->rc_stream, &segcount))
> ^^^^^^^^
>
> 494 return false;
> 495
> 496 /* A bogus segcount causes this buffer overflow check to fail. */
> 497 p = xdr_inline_decode(&rctxt->rc_stream,
> --> 498 segcount * rpcrdma_segment_maxsz * sizeof(*p));
>
>
> segcount is an untrusted u32. On 32bit systems anything >= SIZE_MAX / 16 will
> have an integer overflow and some those values will be accepted by
> xdr_inline_decode().
Yep, this is a bug. This is input parsing/checking code and should
be more careful.
> 499 return p != NULL;
> 500 }
>
> regards,
> dan carpenter
--
Chuck Lever
