* [PATCH net] ipv4: Check attribute length for RTA_GATEWAY
@ 2021-12-11 16:21 David Ahern
2021-12-11 19:13 ` Ido Schimmel
0 siblings, 1 reply; 4+ messages in thread
From: David Ahern @ 2021-12-11 16:21 UTC (permalink / raw)
To: netdev; +Cc: David Ahern, syzbot+d4b9a2851cc3ce998741, Thomas Graf
syzbot reported uninit-value:
============================================================
BUG: KMSAN: uninit-value in fib_get_nhs+0xac4/0x1f80
net/ipv4/fib_semantics.c:708
fib_get_nhs+0xac4/0x1f80 net/ipv4/fib_semantics.c:708
fib_create_info+0x2411/0x4870 net/ipv4/fib_semantics.c:1453
fib_table_insert+0x45c/0x3a10 net/ipv4/fib_trie.c:1224
inet_rtm_newroute+0x289/0x420 net/ipv4/fib_frontend.c:886
Add length checking before using the attribute.
Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
Reported-by: syzbot+d4b9a2851cc3ce998741@syzkaller.appspotmail.com
Signed-off-by: David Ahern <dsahern@kernel.org>
Cc: Thomas Graf <tgraf@suug.ch>
---
I do not have KMSAN setup, so this is based on a code analysis. Before
4e902c57417c fib_get_attr32 was checking the attribute length; the
switch to nla_get_u32 does not.
net/ipv4/fib_semantics.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 3cad543dc747..930843ba3b17 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
return -EINVAL;
}
if (nla) {
+ if (nla_len(nla) < sizeof(__be32)) {
+ NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
+ return -EINVAL;
+ }
fib_cfg.fc_gw4 = nla_get_in_addr(nla);
if (fib_cfg.fc_gw4)
fib_cfg.fc_gw_family = AF_INET;
--
2.24.3 (Apple Git-128)
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH net] ipv4: Check attribute length for RTA_GATEWAY
2021-12-11 16:21 [PATCH net] ipv4: Check attribute length for RTA_GATEWAY David Ahern
@ 2021-12-11 19:13 ` Ido Schimmel
2021-12-11 22:13 ` David Ahern
0 siblings, 1 reply; 4+ messages in thread
From: Ido Schimmel @ 2021-12-11 19:13 UTC (permalink / raw)
To: David Ahern; +Cc: netdev, syzbot+d4b9a2851cc3ce998741, Thomas Graf
On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote:
> syzbot reported uninit-value:
> ============================================================
> BUG: KMSAN: uninit-value in fib_get_nhs+0xac4/0x1f80
> net/ipv4/fib_semantics.c:708
> fib_get_nhs+0xac4/0x1f80 net/ipv4/fib_semantics.c:708
> fib_create_info+0x2411/0x4870 net/ipv4/fib_semantics.c:1453
> fib_table_insert+0x45c/0x3a10 net/ipv4/fib_trie.c:1224
> inet_rtm_newroute+0x289/0x420 net/ipv4/fib_frontend.c:886
>
> Add length checking before using the attribute.
>
> Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
> Reported-by: syzbot+d4b9a2851cc3ce998741@syzkaller.appspotmail.com
> Signed-off-by: David Ahern <dsahern@kernel.org>
> Cc: Thomas Graf <tgraf@suug.ch>
> ---
> I do not have KMSAN setup, so this is based on a code analysis. Before
Was using this in the past:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
> 4e902c57417c fib_get_attr32 was checking the attribute length; the
> switch to nla_get_u32 does not.
>
> net/ipv4/fib_semantics.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index 3cad543dc747..930843ba3b17 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
> return -EINVAL;
> }
> if (nla) {
> + if (nla_len(nla) < sizeof(__be32)) {
> + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
> + return -EINVAL;
> + }
Isn't the problem more general than that? It seems that there is no
minimum length validation to any of the attributes inside RTA_MULTIPATH.
Except maybe RTA_VIA
> fib_cfg.fc_gw4 = nla_get_in_addr(nla);
> if (fib_cfg.fc_gw4)
> fib_cfg.fc_gw_family = AF_INET;
> --
> 2.24.3 (Apple Git-128)
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net] ipv4: Check attribute length for RTA_GATEWAY
2021-12-11 19:13 ` Ido Schimmel
@ 2021-12-11 22:13 ` David Ahern
2021-12-12 8:09 ` Ido Schimmel
0 siblings, 1 reply; 4+ messages in thread
From: David Ahern @ 2021-12-11 22:13 UTC (permalink / raw)
To: Ido Schimmel, David Ahern
Cc: netdev, syzbot+d4b9a2851cc3ce998741, Thomas Graf
On 12/11/21 12:13 PM, Ido Schimmel wrote:
> On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote:
>> syzbot reported uninit-value:
>> ============================================================
>> BUG: KMSAN: uninit-value in fib_get_nhs+0xac4/0x1f80
>> net/ipv4/fib_semantics.c:708
>> fib_get_nhs+0xac4/0x1f80 net/ipv4/fib_semantics.c:708
>> fib_create_info+0x2411/0x4870 net/ipv4/fib_semantics.c:1453
>> fib_table_insert+0x45c/0x3a10 net/ipv4/fib_trie.c:1224
>> inet_rtm_newroute+0x289/0x420 net/ipv4/fib_frontend.c:886
>>
>> Add length checking before using the attribute.
>>
>> Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
>> Reported-by: syzbot+d4b9a2851cc3ce998741@syzkaller.appspotmail.com
>> Signed-off-by: David Ahern <dsahern@kernel.org>
>> Cc: Thomas Graf <tgraf@suug.ch>
>> ---
>> I do not have KMSAN setup, so this is based on a code analysis. Before
>
> Was using this in the past:
> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
thanks for the pointer. I am a bit hardware challenged at the moment for
out of tree features.
>
>> 4e902c57417c fib_get_attr32 was checking the attribute length; the
>> switch to nla_get_u32 does not.
>>
>> net/ipv4/fib_semantics.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
>> index 3cad543dc747..930843ba3b17 100644
>> --- a/net/ipv4/fib_semantics.c
>> +++ b/net/ipv4/fib_semantics.c
>> @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
>> return -EINVAL;
>> }
>> if (nla) {
>> + if (nla_len(nla) < sizeof(__be32)) {
>> + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
>> + return -EINVAL;
>> + }
>
> Isn't the problem more general than that? It seems that there is no
> minimum length validation to any of the attributes inside RTA_MULTIPATH.
> Except maybe RTA_VIA
>
A follow up commit is needed for RTA_FLOW.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net] ipv4: Check attribute length for RTA_GATEWAY
2021-12-11 22:13 ` David Ahern
@ 2021-12-12 8:09 ` Ido Schimmel
0 siblings, 0 replies; 4+ messages in thread
From: Ido Schimmel @ 2021-12-12 8:09 UTC (permalink / raw)
To: David Ahern; +Cc: David Ahern, netdev, syzbot+d4b9a2851cc3ce998741, Thomas Graf
On Sat, Dec 11, 2021 at 03:13:02PM -0700, David Ahern wrote:
> On 12/11/21 12:13 PM, Ido Schimmel wrote:
> > On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote:
> >> syzbot reported uninit-value:
> >> ============================================================
> >> BUG: KMSAN: uninit-value in fib_get_nhs+0xac4/0x1f80
> >> net/ipv4/fib_semantics.c:708
> >> fib_get_nhs+0xac4/0x1f80 net/ipv4/fib_semantics.c:708
> >> fib_create_info+0x2411/0x4870 net/ipv4/fib_semantics.c:1453
> >> fib_table_insert+0x45c/0x3a10 net/ipv4/fib_trie.c:1224
> >> inet_rtm_newroute+0x289/0x420 net/ipv4/fib_frontend.c:886
> >>
> >> Add length checking before using the attribute.
> >>
> >> Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
> >> Reported-by: syzbot+d4b9a2851cc3ce998741@syzkaller.appspotmail.com
> >> Signed-off-by: David Ahern <dsahern@kernel.org>
> >> Cc: Thomas Graf <tgraf@suug.ch>
> >> ---
> >> I do not have KMSAN setup, so this is based on a code analysis. Before
> >
> > Was using this in the past:
> > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
>
> thanks for the pointer. I am a bit hardware challenged at the moment for
> out of tree features.
>
> >
> >> 4e902c57417c fib_get_attr32 was checking the attribute length; the
> >> switch to nla_get_u32 does not.
> >>
> >> net/ipv4/fib_semantics.c | 4 ++++
> >> 1 file changed, 4 insertions(+)
> >>
> >> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> >> index 3cad543dc747..930843ba3b17 100644
> >> --- a/net/ipv4/fib_semantics.c
> >> +++ b/net/ipv4/fib_semantics.c
> >> @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
> >> return -EINVAL;
> >> }
> >> if (nla) {
> >> + if (nla_len(nla) < sizeof(__be32)) {
> >> + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
> >> + return -EINVAL;
> >> + }
> >
> > Isn't the problem more general than that? It seems that there is no
> > minimum length validation to any of the attributes inside RTA_MULTIPATH.
> > Except maybe RTA_VIA
> >
>
> A follow up commit is needed for RTA_FLOW.
The same problem seems to exists in the delete path and IPv6. See
fib_nh_match() and ip6_route_multipath_add(), for example.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-12-12 8:09 UTC | newest]
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2021-12-11 16:21 [PATCH net] ipv4: Check attribute length for RTA_GATEWAY David Ahern
2021-12-11 19:13 ` Ido Schimmel
2021-12-11 22:13 ` David Ahern
2021-12-12 8:09 ` Ido Schimmel
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