From 0b28000b64f40dd29a730507aa0447231960cfb8 Mon Sep 17 00:00:00 2001 From: Edward Adam Davis Date: Thu, 7 May 2026 20:50:10 +0800 Subject: [PATCH] RDMA/nldev: Add mutual exclusion in nldev_dellink() We must serialize calls to nldev_dellink() or risk a crash as syzbot reported: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] Call Trace: udp_tunnel_sock_release+0x6d/0x80 net/ipv4/udp_tunnel_core.c:197 rxe_release_udp_tunnel drivers/infiniband/sw/rxe/rxe_net.c:294 [inline] rxe_sock_put drivers/infiniband/sw/rxe/rxe_net.c:639 [inline] rxe_net_del+0xfb/0x290 drivers/infiniband/sw/rxe/rxe_net.c:660 rxe_dellink+0x15/0x20 drivers/infiniband/sw/rxe/rxe.c:254 Fixes: a60e3f3d6fba ("RDMA/nldev: Add dellink function pointer") Reported-by: syzbot+d8f76778263ab65c2b21@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d8f76778263ab65c2b21 Tested-by: syzbot+d8f76778263ab65c2b21@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis Link: https://patch.msgid.link/tencent_611BEB4B141B1A2526BAA3BBB2335F9E9108@qq.com Reviewed-by: Zhu Yanjun Signed-off-by: Leon Romanovsky --- drivers/infiniband/core/nldev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c index 96c745d5bac4..5aaba2b9746b 100644 --- a/drivers/infiniband/core/nldev.c +++ b/drivers/infiniband/core/nldev.c @@ -51,6 +51,7 @@ * a controlled QKEY. */ static bool privileged_qkey; +static DEFINE_MUTEX(nldev_dellink_mutex); typedef int (*res_fill_func_t)(struct sk_buff*, bool, struct rdma_restrack_entry*, uint32_t); @@ -1846,7 +1847,9 @@ static int nldev_dellink(struct sk_buff *skb, struct nlmsghdr *nlh, * implicitly scoped to the driver supporting dynamic link deletion like RXE. */ if (device->link_ops && device->link_ops->dellink) { + mutex_lock(&nldev_dellink_mutex); err = device->link_ops->dellink(device); + mutex_unlock(&nldev_dellink_mutex); if (err) return err; }