[PATCH net] tipc: fix panic in tipc_udp_nl_dump_remoteip() using bearer as udp without check

[PATCH net] tipc: fix panic in tipc_udp_nl_dump_remoteip() using bearer as udp without check

[Haixia Qu]

When TIPC_NL_UDP_GET_REMOTEIP cmd calls tipc_udp_nl_dump_remoteip()
with media name set to a l2 name, kernel panics [1].

The reproduction steps:
1. create a tun interface
2. enable l2 bearer
3. TIPC_NL_UDP_GET_REMOTEIP with media name set to tun

the ub was in fact a struct dev.

when bid != 0 && skip_cnt != 0, bearer_list[bid] may be NULL or
other media when other thread changes it.

fix this by checking media_id.

[1]
tipc: Started in network mode
tipc: Node identity 8af312d38a21, cluster identity 4711
tipc: Enabled bearer <eth:syz_tun>, priority 1
Oops: general protection fault
KASAN: null-ptr-deref in range
CPU: 1 UID: 1000 PID: 559 Comm: poc Not tainted 6.16.0-rc1+ #117 PREEMPT
Hardware name: QEMU Ubuntu 24.04 PC
RIP: 0010:tipc_udp_nl_dump_remoteip+0x4a4/0x8f0

Fixes: 832629ca5c313 ("tipc: add UDP remoteip dump to netlink API")
Signed-off-by: Haixia Qu <hxqu@hillstonenet.com>
---
 net/tipc/udp_media.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index 108a4cc2e001..258d6aa4f21a 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -489,7 +489,7 @@ int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb)
 
 		rtnl_lock();
 		b = tipc_bearer_find(net, bname);
-		if (!b) {
+		if (!b || b->bcast_addr.media_id != TIPC_MEDIA_TYPE_UDP) {
 			rtnl_unlock();
 			return -EINVAL;
 		}
@@ -500,7 +500,7 @@ int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb)
 
 		rtnl_lock();
 		b = rtnl_dereference(tn->bearer_list[bid]);
-		if (!b) {
+		if (!b || b->bcast_addr.media_id != TIPC_MEDIA_TYPE_UDP) {
 			rtnl_unlock();
 			return -EINVAL;
 		}
-- 
2.43.0

RE: [PATCH net] tipc: fix panic in tipc_udp_nl_dump_remoteip() using bearer as udp without check

[Tung Quang Nguyen]

>Subject: [PATCH net] tipc: fix panic in tipc_udp_nl_dump_remoteip() using
>bearer as udp without check
Please rephrase the name of this patch and add version for each change.
Example for your next sending:
[PATCH v4 net] tipc: fix null-ptr-deref when acquiring remote ip of ethernet bearer
>
>When TIPC_NL_UDP_GET_REMOTEIP cmd calls tipc_udp_nl_dump_remoteip()
>with media name set to a l2 name, kernel panics [1].
Remove above description because new patch name is descriptive enough.
>
>The reproduction steps:
>1. create a tun interface
>2. enable l2 bearer
>3. TIPC_NL_UDP_GET_REMOTEIP with media name set to tun
>
>the ub was in fact a struct dev.
>
>when bid != 0 && skip_cnt != 0, bearer_list[bid] may be NULL or other media
>when other thread changes it.
>
>fix this by checking media_id.
>
>[1]
>tipc: Started in network mode
>tipc: Node identity 8af312d38a21, cluster identity 4711
>tipc: Enabled bearer <eth:syz_tun>, priority 1
>Oops: general protection fault
>KASAN: null-ptr-deref in range
>CPU: 1 UID: 1000 PID: 559 Comm: poc Not tainted 6.16.0-rc1+ #117 PREEMPT
>Hardware name: QEMU Ubuntu 24.04 PC
>RIP: 0010:tipc_udp_nl_dump_remoteip+0x4a4/0x8f0
Please move this observation right after the reproduction steps.

>Fixes: 832629ca5c313 ("tipc: add UDP remoteip dump to netlink API")
>Signed-off-by: Haixia Qu <hxqu@hillstonenet.com>
>---
Please add "v4: <the reason of version up>" here

Note: Please remove email domain ericsson.com of Jon and Richard because it is not existing anymore.