KMSAN reported an uninit-value access in __inet_bind() when binding an RDS TCP socket. The uninitialized memory originates from rds_tcp_conn_alloc(), which uses kmem_cache_alloc() to allocate the rds_tcp_connection structure. Specifically, the field 't_client_port_group' is incremented in rds_tcp_conn_path_connect() without being initialized first: if (++tc->t_client_port_group >= port_groups) Since kmem_cache_alloc() does not zero the memory, this field contains garbage, leading to the KMSAN report. Fix this by using kmem_cache_zalloc() to ensure the structure is zero-initialized upon allocation. Reported-by: syzbot+aae646f09192f72a68dc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=aae646f09192f72a68dc Tested-by: syzbot+aae646f09192f72a68dc@syzkaller.appspotmail.com Fixes: a20a6992558f ("net/rds: Encode cp_index in TCP source port") Signed-off-by: Tabrez Ahmed --- v2: - Updated Fixes tag to point to commit a20a6992558f as requested by Charalampos Mitrodimas and Allison Henderson. - Explicitly mentioned 't_client_port_group' in the commit message. - Fixed line wrapping to be under 75 characters. net/rds/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/rds/tcp.c b/net/rds/tcp.c index 45484a93d75f..04f310255692 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -373,7 +373,7 @@ static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp) int ret = 0; for (i = 0; i < RDS_MPATH_WORKERS; i++) { - tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp); + tc = kmem_cache_zalloc(rds_tcp_conn_slab, gfp); if (!tc) { ret = -ENOMEM; goto fail; -- 2.43.0