rds: fix out-of-bounds conn_path walks via handshake exthdrs

Both the lane and the connection-generation negotiation are driven by
extension headers in handshake packets, and both are processed
unconditionally, even on transports that are not multipath capable.
A non-MP connection (t_mp_capable unset) owns exactly one
rds_conn_path slot, so a peer claiming up to RDS_MPATH_WORKERS lanes
makes every subsequent fan-out walk conn->c_path[0..7] at 504-byte
strides past the single allocated slot (KASAN: "Read of size 8 in
rds_conn_path_connect_if_down"); the generation negotiation opens a
similar out-of-bounds walk on the same array.

Only process handshake extension headers when the connection's
transport is multipath capable, so a peer can never make us walk
lanes that do not exist.  Both call sites in rds_recv_incoming() are
gated.

This is a port of the Oracle UEK fix for the same issue, picked up
where Paula's series of the same change left off.

This issue was discovered by Tencent CodeBuddy Security.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/netdev/20260825120132.51636-1-pamoutafpro@gmail.com/
Link: https://github.com/oracle/linux-uek/commit/2fdeb0513f18
Fixes: 840df162b3eb ("rds: reduce memory footprint for RDS when transport is RDMA")
Fixes: 905dd4184e07 ("RDS: TCP: Track peer's connection generation number")
Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
Reviewed-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20261012025336.54756-1-bsdhenrymartin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions