During initialisation of the SMC module initialize smc_v4/6_hashinfo before calling smc_nl_init(), proto_register() or sock_register(), to avoid a race that can cause use of an uninitialised pointer in case an smc protocol is called before the module is done initialising.
syzbot report: KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] Call Trace: <TASK> smc_diag_dump+0x59/0xa0 net/smc/smc_diag.c:236 netlink_dump+0x647/0xd80 net/netlink/af_netlink.c:2325 __netlink_dump_start+0x59f/0x780 net/netlink/af_netlink.c:2440 netlink_dump_start include/linux/netlink.h:339 [inline] smc_diag_handler_dump+0x1ab/0x250 net/smc/smc_diag.c:251 sock_diag_rcv_msg+0x3dc/0x5f0 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline] netlink_unicast+0x7f0/0x990 net/netlink/af_netlink.c:1357 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
Fixes: f16a7dd5cf27 ("smc: netlink interface for SMC sockets") Reported-by: syzbot+f69bfae0a4eb29976e44@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f69bfae0a4eb29976e44 Signed-off-by: Alexandra Winter wintera@linux.ibm.com --- net/smc/af_smc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index f97f77b041d9..b0f4405fb714 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -3524,6 +3524,9 @@ static int __init smc_init(void) goto out_pernet_subsys_stat; smc_clc_init();
+ INIT_HLIST_HEAD(&smc_v4_hashinfo.ht); + INIT_HLIST_HEAD(&smc_v6_hashinfo.ht); + rc = smc_nl_init(); if (rc) goto out_ism; @@ -3581,8 +3584,6 @@ static int __init smc_init(void) pr_err("%s: sock_register fails with %d\n", __func__, rc); goto out_proto6; } - INIT_HLIST_HEAD(&smc_v4_hashinfo.ht); - INIT_HLIST_HEAD(&smc_v6_hashinfo.ht);
rc = smc_ib_register_client(); if (rc) {