In the Linux kernel, the following vulnerability has been resolved:
RDMA/rxe: Fix integer overflow in mr_check_range() leading to OOB access
mr_check_range() validates that [iova, iova+length) falls within the
registered MR range using wraparound-prone arithmetic:
if (iova ibmr.iova ||
iova + length > mr->ibmr.iova + mr->ibmr.length)
A remote peer can craft an RDMA-Write/Read RETH so that iova + length
wraps to 0 (e.g. iova=0xfffffffffffffff8, length=8), bypassing the
check. rxe_mr_iova_to_index() then computes a huge index (int idx, only
guarded by WARN_ON) and rxe_mr_copy_xarray() dereferences
mr->page_info[huge], causing an out-of-bounds read/write and a kernel
oops that is triggerable by an unauthenticated remote peer.
Rewrite the check in overflow-safe form; the first two clauses guarantee
that the subsequent subtractions do not underflow:
if (iova ibmr.iova ||
length > mr->ibmr.length ||
iova – mr->ibmr.iova > mr->ibmr.length – length)
With the fix, mr_check_range() returns -EINVAL for the crafted iova and
the responder reports REMOTE_ACCESS_ERROR instead of triggering the OOB.
