From: Eric Dumazet edumazet@google.com
[ Upstream commit 624085a31c1ad6a80b1e53f686bf6ee92abbf6e8 ]
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 Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 a9e1d7918d14..6ffa05298cc0 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;