On Thu, 2024-02-01 at 00:23 +0900, Shigeru Yoshida wrote:
> 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: [email protected]
> Closes: https://syzkaller.appspot.com/bug?extid=5142b87a9abc510e14fa [1]
> Signed-off-by: Shigeru Yoshida <[email protected]>
> ---
> 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.
Cheers,
Paolo
On Tue, 06 Feb 2024 08:53:14 +0100, Paolo Abeni wrote:
> On Thu, 2024-02-01 at 00:23 +0900, Shigeru Yoshida wrote:
>> 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: [email protected]
>> Closes: https://syzkaller.appspot.com/bug?extid=5142b87a9abc510e14fa [1]
>> Signed-off-by: Shigeru Yoshida <[email protected]>
>> ---
>> 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
>