Commit 2ac09b5353fe for kernel

commit 2ac09b5353fe6858411fdc8c6efa60d832e20f13
Author: Greg Marsden <greg.marsden@oracle.com>
Date:   Sat Sep 5 10:00:41 2026 -0700

    net/rds: fix tcp stream corruption with large pages

    rds_message_map_pages() assigns PAGE_SIZE bytes to every
    scatterlist entry, even when total_len ends in a partial page. The RDS
    congestion map is defined as 8192 bytes, so on systems with PAGE_SIZE
    greater than 8192 the scatterlist maps bytes beyond the end of the
    congestion map.  RDS-TCP transmits the SG contents according to those
    lengths, so the extra bytes become part of the TCP RDS stream and are
    interpreted as subsequent RDS message headers, corrupting the stream.

    Limit the final scatterlist mapping to the number of bytes remaining.
    This has no effect on systems with a 4K page size and allows RDS-TCP to
    be used on systems with 16K and larger page sizes.

    The RDS selftest, which previously hung on 16K pages, now passes.

    Fixes: 7875e18e0996 ("RDS: Message parsing")
    Signed-off-by: Greg Marsden <greg.marsden@oracle.com>
    Reviewed-by: Allison Henderson <achender@kernel.org>
    Link: https://patch.msgid.link/apxJjxvStibPI0AS@oracle.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/rds/message.c b/net/rds/message.c
index f25f2592586f..47d5e9ab9b10 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -431,7 +431,9 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in
 	for (i = 0; i < rm->data.op_nents; ++i) {
 		sg_set_page(&rm->data.op_sg[i],
 				virt_to_page((void *)page_addrs[i]),
-				PAGE_SIZE, 0);
+				i == rm->data.op_nents - 1
+					? total_len - (i * PAGE_SIZE)
+					: PAGE_SIZE, 0);
 	}

 	return rm;