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.

Fixes: d96962e6d0e2 ("svcrdma: Use the new parsed chunk list when pulling Read chunks")
Cc: stable@vger.kernel.org
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260526-rpc-kernel-bugs-v1-1-e251306ccca9@oracle.com
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

0 files changed, 0 insertions, 0 deletions