netdev - Re: [PATCH net v3] tipc: Change nla_policy for bearer-related names to NLA_NUL

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Date: Mon, 30 Oct 2023 13:00:18 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Shigeru Yoshida <syoshida@...hat.com>
Cc: jmaloy@...hat.com, ying.xue@...driver.com, netdev@...r.kernel.org,
	tipc-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	syzbot+5138ca807af9d2b42574@...kaller.appspotmail.com,
	syzbot+9425c47dccbcb4c17d51@...kaller.appspotmail.com
Subject: Re: [PATCH net v3] tipc: Change nla_policy for bearer-related names
 to NLA_NUL_STRING

Mon, Oct 30, 2023 at 08:55:40AM CET, syoshida@...hat.com wrote:
>syzbot reported the following uninit-value access issue [1]:
>
>=====================================================
>BUG: KMSAN: uninit-value in strlen lib/string.c:418 [inline]
>BUG: KMSAN: uninit-value in strstr+0xb8/0x2f0 lib/string.c:756
> strlen lib/string.c:418 [inline]
> strstr+0xb8/0x2f0 lib/string.c:756
> tipc_nl_node_reset_link_stats+0x3ea/0xb50 net/tipc/node.c:2595
> genl_family_rcv_msg_doit net/netlink/genetlink.c:971 [inline]
> genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
> genl_rcv_msg+0x11ec/0x1290 net/netlink/genetlink.c:1066
> netlink_rcv_skb+0x371/0x650 net/netlink/af_netlink.c:2545
> genl_rcv+0x40/0x60 net/netlink/genetlink.c:1075
> netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
> netlink_unicast+0xf47/0x1250 net/netlink/af_netlink.c:1368
> netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
> sock_sendmsg_nosec net/socket.c:730 [inline]
> sock_sendmsg net/socket.c:753 [inline]
> ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2541
> ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2595
> __sys_sendmsg net/socket.c:2624 [inline]
> __do_sys_sendmsg net/socket.c:2633 [inline]
> __se_sys_sendmsg net/socket.c:2631 [inline]
> __x64_sys_sendmsg+0x307/0x490 net/socket.c:2631
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
>Uninit was created at:
> slab_post_alloc_hook+0x12f/0xb70 mm/slab.h:767
> slab_alloc_node mm/slub.c:3478 [inline]
> kmem_cache_alloc_node+0x577/0xa80 mm/slub.c:3523
> kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:559
> __alloc_skb+0x318/0x740 net/core/skbuff.c:650
> alloc_skb include/linux/skbuff.h:1286 [inline]
> netlink_alloc_large_skb net/netlink/af_netlink.c:1214 [inline]
> netlink_sendmsg+0xb34/0x13d0 net/netlink/af_netlink.c:1885
> sock_sendmsg_nosec net/socket.c:730 [inline]
> sock_sendmsg net/socket.c:753 [inline]
> ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2541
> ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2595
> __sys_sendmsg net/socket.c:2624 [inline]
> __do_sys_sendmsg net/socket.c:2633 [inline]
> __se_sys_sendmsg net/socket.c:2631 [inline]
> __x64_sys_sendmsg+0x307/0x490 net/socket.c:2631
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
>TIPC bearer-related names including link names must be null-terminated
>strings. If a link name which is not null-terminated is passed through
>netlink, strstr() and similar functions can cause buffer overrun. This
>causes the above issue.
>
>This patch changes the nla_policy for bearer-related names from NLA_STRING
>to NLA_NUL_STRING. This resolves the issue by ensuring that only
>null-terminated strings are accepted as bearer-related names.
>
>syzbot reported similar uninit-value issue related to bearer names [2]. The
>root cause of this issue is that a non-null-terminated bearer name was
>passed. This patch also resolved this issue.
>
>Fixes: 7be57fc69184 ("tipc: add link get/dump to new netlink api")
>Fixes: 0655f6a8635b ("tipc: add bearer disable/enable to new netlink api")
>Reported-and-tested-by: syzbot+5138ca807af9d2b42574@...kaller.appspotmail.com
>Closes: https://syzkaller.appspot.com/bug?extid=5138ca807af9d2b42574 [1]
>Reported-and-tested-by: syzbot+9425c47dccbcb4c17d51@...kaller.appspotmail.com
>Closes: https://syzkaller.appspot.com/bug?extid=9425c47dccbcb4c17d51 [2]
>Signed-off-by: Shigeru Yoshida <syoshida@...hat.com>

Reviewed-by: Jiri Pirko <jiri@...dia.com>