* [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv()
@ 2021-06-24 10:07 Eric Dumazet
2021-06-24 13:15 ` Paolo Abeni
2021-06-24 19:50 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Eric Dumazet @ 2021-06-24 10:07 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, Paolo Abeni, Tom Herbert
From: Eric Dumazet <edumazet@google.com>
First problem is that optlen is fetched without checking
there is more than one byte to parse.
Fix this by taking care of IPV6_TLV_PAD1 before
fetching optlen (under appropriate sanity checks against len)
Second problem is that IPV6_TLV_PADN checks of zero
padding are performed before the check of remaining length.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: c1412fce7ecc ("net/ipv6/exthdrs.c: Strict PadN option checking")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Tom Herbert <tom@herbertland.com>
---
v2: Removed not needed optlen assignment for IPV6_TLV_PAD1 handling,
added the Fixes: tag for first problem, feedback from Paolo, thanks !
net/ipv6/exthdrs.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 6f7da8f3e2e5849f917853984c69bf02a0f1e27c..26882e165c9e37a105f988020031f03d6b1a5cf9 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -135,18 +135,23 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
len -= 2;
while (len > 0) {
- int optlen = nh[off + 1] + 2;
- int i;
+ int optlen, i;
- switch (nh[off]) {
- case IPV6_TLV_PAD1:
- optlen = 1;
+ if (nh[off] == IPV6_TLV_PAD1) {
padlen++;
if (padlen > 7)
goto bad;
- break;
+ off++;
+ len--;
+ continue;
+ }
+ if (len < 2)
+ goto bad;
+ optlen = nh[off + 1] + 2;
+ if (optlen > len)
+ goto bad;
- case IPV6_TLV_PADN:
+ if (nh[off] == IPV6_TLV_PADN) {
/* RFC 2460 states that the purpose of PadN is
* to align the containing header to multiples
* of 8. 7 is therefore the highest valid value.
@@ -163,12 +168,7 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
if (nh[off + i] != 0)
goto bad;
}
- break;
-
- default: /* Other TLV code so scan list */
- if (optlen > len)
- goto bad;
-
+ } else {
tlv_count++;
if (tlv_count > max_count)
goto bad;
@@ -188,7 +188,6 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
return false;
padlen = 0;
- break;
}
off += optlen;
len -= optlen;
--
2.32.0.288.g62a8d224e6-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv()
2021-06-24 10:07 [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv() Eric Dumazet
@ 2021-06-24 13:15 ` Paolo Abeni
2021-06-24 19:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Paolo Abeni @ 2021-06-24 13:15 UTC (permalink / raw)
To: Eric Dumazet, David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Tom Herbert
On Thu, 2021-06-24 at 03:07 -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> First problem is that optlen is fetched without checking
> there is more than one byte to parse.
>
> Fix this by taking care of IPV6_TLV_PAD1 before
> fetching optlen (under appropriate sanity checks against len)
>
> Second problem is that IPV6_TLV_PADN checks of zero
> padding are performed before the check of remaining length.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Fixes: c1412fce7ecc ("net/ipv6/exthdrs.c: Strict PadN option checking")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Tom Herbert <tom@herbertland.com>
> ---
> v2: Removed not needed optlen assignment for IPV6_TLV_PAD1 handling,
> added the Fixes: tag for first problem, feedback from Paolo, thanks !
>
> net/ipv6/exthdrs.c | 27 +++++++++++++--------------
> 1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
> index 6f7da8f3e2e5849f917853984c69bf02a0f1e27c..26882e165c9e37a105f988020031f03d6b1a5cf9 100644
> --- a/net/ipv6/exthdrs.c
> +++ b/net/ipv6/exthdrs.c
> @@ -135,18 +135,23 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
> len -= 2;
>
> while (len > 0) {
> - int optlen = nh[off + 1] + 2;
> - int i;
> + int optlen, i;
>
> - switch (nh[off]) {
> - case IPV6_TLV_PAD1:
> - optlen = 1;
> + if (nh[off] == IPV6_TLV_PAD1) {
> padlen++;
> if (padlen > 7)
> goto bad;
> - break;
> + off++;
> + len--;
> + continue;
> + }
> + if (len < 2)
> + goto bad;
> + optlen = nh[off + 1] + 2;
> + if (optlen > len)
> + goto bad;
>
> - case IPV6_TLV_PADN:
> + if (nh[off] == IPV6_TLV_PADN) {
> /* RFC 2460 states that the purpose of PadN is
> * to align the containing header to multiples
> * of 8. 7 is therefore the highest valid value.
> @@ -163,12 +168,7 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
> if (nh[off + i] != 0)
> goto bad;
> }
> - break;
> -
> - default: /* Other TLV code so scan list */
> - if (optlen > len)
> - goto bad;
> -
> + } else {
> tlv_count++;
> if (tlv_count > max_count)
> goto bad;
> @@ -188,7 +188,6 @@ static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
> return false;
>
> padlen = 0;
> - break;
> }
> off += optlen;
> len -= optlen;
LGTM!
Reviewd-by: Paolo Abeni <pabeni@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv()
2021-06-24 10:07 [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv() Eric Dumazet
2021-06-24 13:15 ` Paolo Abeni
@ 2021-06-24 19:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-06-24 19:50 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, kuba, netdev, edumazet, pabeni, tom
Hello:
This patch was applied to netdev/net.git (refs/heads/master):
On Thu, 24 Jun 2021 03:07:20 -0700 you wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> First problem is that optlen is fetched without checking
> there is more than one byte to parse.
>
> Fix this by taking care of IPV6_TLV_PAD1 before
> fetching optlen (under appropriate sanity checks against len)
>
> [...]
Here is the summary with links:
- [v2,net] ipv6: fix out-of-bound access in ip6_parse_tlv()
https://git.kernel.org/netdev/net/c/624085a31c1a
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-06-24 19:50 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-24 10:07 [PATCH v2 net] ipv6: fix out-of-bound access in ip6_parse_tlv() Eric Dumazet
2021-06-24 13:15 ` Paolo Abeni
2021-06-24 19:50 ` patchwork-bot+netdevbpf
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.