CVE-2026-89526

In the Linux kernel, the following vulnerability has been resolved:

svcrdma: Validate Read chunk positions before reconstruction

The RPC/RDMA Read chunk position field is supplied by the remote

client and stored verbatim in the parsed chunk list.

xdr_count_read_segments() checks only 4-byte alignment; it never

compares the position against the received inline body length.

In the single-chunk path, svc_rdma_read_complete_one() splits the

head and tail kvecs at ch_position. A position past the inline

body underflows the tail length, exposing adjacent slab memory to

the upper XDR decoder.

In the multi-chunk path, svc_rdma_read_multiple_chunks() computes

gap lengths between chunks as unsigned subtractions from

ch_position. Overlapping Read chunks cause these subtractions to

underflow. A final position past the inline body likewise

underflows the trailing gap length. svc_rdma_copy_inline_range()

then copies past the receive buffer into request pages that are

returned to the client through the Reply channel.

Bound inline-range copies in svc_rdma_copy_inline_range() against

the decoded inline RPC body saved in rc_saved_arg. Reject a

single Read chunk positioned beyond that body, and reject

multi-chunk lists where accumulated read bytes exceed the next

chunk's position. Apply the same position and overlap checks in

the call-chunk interleaving path.