On Tue, 06 Feb 2024 08:53:14 +0100, Paolo Abeni wrote:
On Thu, 2024-02-01 at 00:23 +0900, Shigeru Yoshida wrote:
quoted
syzbot reported the following general protection fault [1]:
general protection fault, probably for non-canonical address 0xdffffc0000000010: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000080-0x0000000000000087]
...
RIP: 0010:tipc_udp_is_known_peer+0x9c/0x250 net/tipc/udp_media.c:291
...
Call Trace:
<TASK>
tipc_udp_nl_bearer_add+0x212/0x2f0 net/tipc/udp_media.c:646
tipc_nl_bearer_add+0x21e/0x360 net/tipc/bearer.c:1089
genl_family_rcv_msg_doit+0x1fc/0x2e0 net/netlink/genetlink.c:972
genl_family_rcv_msg net/netlink/genetlink.c:1052 [inline]
genl_rcv_msg+0x561/0x800 net/netlink/genetlink.c:1067
netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2544
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
netlink_unicast+0x53b/0x810 net/netlink/af_netlink.c:1367
netlink_sendmsg+0x8b7/0xd70 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xd5/0x180 net/socket.c:745
____sys_sendmsg+0x6ac/0x940 net/socket.c:2584
___sys_sendmsg+0x135/0x1d0 net/socket.c:2638
__sys_sendmsg+0x117/0x1e0 net/socket.c:2667
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b
The cause of this issue is that when tipc_nl_bearer_add() is called with
the TIPC_NLA_BEARER_UDP_OPTS attribute, tipc_udp_nl_bearer_add() is called
even if the bearer is not UDP.
tipc_udp_is_known_peer() called by tipc_udp_nl_bearer_add() assumes that
the media_ptr field of the tipc_bearer has an udp_bearer type object, so
the function goes crazy for non-UDP bearers.
This patch fixes the issue by checking the bearer type before calling
tipc_udp_nl_bearer_add() in tipc_nl_bearer_add().
Fixes: ef20cd4dd163 ("tipc: introduce UDP replicast")
Reported-and-tested-by: <redacted>
Closes: https://syzkaller.appspot.com/bug?extid=5142b87a9abc510e14fa [1]
Signed-off-by: Shigeru Yoshida <redacted>
---
net/tipc/bearer.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 2cde375477e3..878415c43527 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -1086,6 +1086,12 @@ int tipc_nl_bearer_add(struct sk_buff *skb, struct genl_info *info)
#ifdef CONFIG_TIPC_MEDIA_UDP
if (attrs[TIPC_NLA_BEARER_UDP_OPTS]) {
+ if (b->media->type_id != TIPC_MEDIA_TYPE_UDP) {
+ rtnl_unlock();
+ NL_SET_ERR_MSG(info->extack, "UDP option is unsupported");
+ return -EINVAL;
+ }
+
The patch LGTM, thanks!
As a side note, this function could probably deserve a net-next follow-
up consolidation the error paths under a common label.
Thank you for commenting. I'll make a patch to clean up the error paths.
Thanks,
Shigeru
Cheers,
Paolo