[PATCH net] ipv6: fix out-of-bound access in ip6_parse_tlv()
flat view
STALE1930d
From: Eric Dumazet <hidden>
Date: 2021-06-23 19:44:00
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
From: Eric Dumazet <redacted>
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: c1412fce7ecc ("net/ipv6/exthdrs.c: Strict PadN option checking")
Signed-off-by: Eric Dumazet <redacted>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Tom Herbert <redacted>
---
Only compiled, I would appreciate a solid review of this patch before merging it, thanks !
net/ipv6/exthdrs.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 6f7da8f3e2e5849f917853984c69bf02a0f1e27c..007959d4d3748f1e21f83946024a9967d08b25b6 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c@@ -135,18 +135,24 @@ 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: + if (nh[off] == IPV6_TLV_PAD1) { optlen = 1; 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 +169,7 @@ 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 +189,6 @@ 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