In the Linux kernel, the following vulnerability has been resolved: svcrdma: Address an integer overflow Dan Carpenter reports: > 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().
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.