syzbot reported the following uninit-value access issue:
=====================================================
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
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 resolves the issue by using nla_strscpy() to ensure the link
name is null-terminated.
Fixes: ae36342b50a9 ("tipc: add link stat reset to new netlink api")
Reported-and-tested-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=5138ca807af9d2b42574
Signed-off-by: Shigeru Yoshida <[email protected]>
---
v1->v2:
- Use nla_strscpy()
- Fix similar bugs in other functions other than syzbot reported
---
net/tipc/node.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 3105abe97bb9..2121908e56c1 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2419,7 +2419,7 @@ int tipc_nl_node_set_link(struct sk_buff *skb, struct genl_info *info)
int err;
int res = 0;
int bearer_id;
- char *name;
+ char name[TIPC_MAX_LINK_NAME];
struct tipc_link *link;
struct tipc_node *node;
struct sk_buff_head xmitq;
@@ -2440,7 +2440,7 @@ int tipc_nl_node_set_link(struct sk_buff *skb, struct genl_info *info)
if (!attrs[TIPC_NLA_LINK_NAME])
return -EINVAL;
- name = nla_data(attrs[TIPC_NLA_LINK_NAME]);
+ nla_strscpy(name, attrs[TIPC_NLA_LINK_NAME], TIPC_MAX_LINK_NAME);
if (strcmp(name, tipc_bclink_name) == 0)
return tipc_nl_bc_link_set(net, attrs);
@@ -2500,7 +2500,7 @@ int tipc_nl_node_get_link(struct sk_buff *skb, struct genl_info *info)
struct net *net = genl_info_net(info);
struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
struct tipc_nl_msg msg;
- char *name;
+ char name[TIPC_MAX_LINK_NAME];
int err;
msg.portid = info->snd_portid;
@@ -2518,7 +2518,7 @@ int tipc_nl_node_get_link(struct sk_buff *skb, struct genl_info *info)
if (!attrs[TIPC_NLA_LINK_NAME])
return -EINVAL;
- name = nla_data(attrs[TIPC_NLA_LINK_NAME]);
+ nla_strscpy(name, attrs[TIPC_NLA_LINK_NAME], TIPC_MAX_LINK_NAME);
msg.skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
if (!msg.skb)
@@ -2563,7 +2563,7 @@ int tipc_nl_node_get_link(struct sk_buff *skb, struct genl_info *info)
int tipc_nl_node_reset_link_stats(struct sk_buff *skb, struct genl_info *info)
{
int err;
- char *link_name;
+ char link_name[TIPC_MAX_LINK_NAME];
unsigned int bearer_id;
struct tipc_link *link;
struct tipc_node *node;
@@ -2584,7 +2584,7 @@ int tipc_nl_node_reset_link_stats(struct sk_buff *skb, struct genl_info *info)
if (!attrs[TIPC_NLA_LINK_NAME])
return -EINVAL;
- link_name = nla_data(attrs[TIPC_NLA_LINK_NAME]);
+ nla_strscpy(link_name, attrs[TIPC_NLA_LINK_NAME], TIPC_MAX_LINK_NAME);
err = -EINVAL;
if (!strcmp(link_name, tipc_bclink_name)) {
--
2.41.0
On Sat, 21 Oct 2023 01:34:15 +0900 Shigeru Yoshida wrote:
> 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.
If strings need to be null-terminated you should switch the policy here
https://elixir.bootlin.com/linux/v6.6-rc6/source/net/tipc/netlink.c#L91
from NLA_STRING to NLA_NUL_STRING, no?
--
pw-bot: cr
On Mon, 23 Oct 2023 15:53:14 -0700, Jakub Kicinski wrote:
> On Sat, 21 Oct 2023 01:34:15 +0900 Shigeru Yoshida wrote:
>> 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.
>
> If strings need to be null-terminated you should switch the policy here
> https://elixir.bootlin.com/linux/v6.6-rc6/source/net/tipc/netlink.c#L91
> from NLA_STRING to NLA_NUL_STRING, no?
Thank you so much for the feedback. As I'm not so familiar with
Netlink, I'll study NLA_NUL_STRING a bit more and make an updated
patch.
Thanks,
Shigeru
> --
> pw-bot: cr
>