[PATCH net] rds: tcp: fix uninit-value in __inet_bind

[Tabrez Ahmed <tabreztalks@gmail.com>]

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.

The structure is not zero-initialized, leaving random data in its fields.
When the networking stack later tries to bind the socket using these dirty values, KMSAN flags the uninitialized access.

Fix this by using kmem_cache_zalloc() instead of kmem_cache_alloc() to ensure the structure is zeroed out 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: 70041088e3b9 ("RDS: Add TCP transport to RDS")

Signed-off-by: Tabrez Ahmed <tabreztalks@gmail.com>
---
This is my first patch. Any feedback is appreciated!

 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