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| author | Sabrina Dubroca <sd@queasysnail.net> | 2017-07-19 22:28:55 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-07-19 22:50:14 -0700 |
| commit | 6399f1fae4ec29fab5ec76070435555e256ca3a6 (patch) | |
| tree | 3bf30f18bbd1c9eb4b37786cba7fe73e70ea014b | |
| parent | 1e6c22aef28364dcc5f03c04a05ec463bc2b3431 (diff) | |
| download | linux-6399f1fae4ec29fab5ec76070435555e256ca3a6.tar.bz2 | |
ipv6: avoid overflow of offset in ip6_find_1stfragopt
In some cases, offset can overflow and can cause an infinite loop in
ip6_find_1stfragopt(). Make it unsigned int to prevent the overflow, and
cap it at IPV6_MAXPLEN, since packets larger than that should be invalid.
This problem has been here since before the beginning of git history.
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv6/output_core.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c index e9065b8d3af8..abb2c307fbe8 100644 --- a/net/ipv6/output_core.c +++ b/net/ipv6/output_core.c @@ -78,7 +78,7 @@ EXPORT_SYMBOL(ipv6_select_ident); int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) { - u16 offset = sizeof(struct ipv6hdr); + unsigned int offset = sizeof(struct ipv6hdr); unsigned int packet_len = skb_tail_pointer(skb) - skb_network_header(skb); int found_rhdr = 0; @@ -86,6 +86,7 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) while (offset <= packet_len) { struct ipv6_opt_hdr *exthdr; + unsigned int len; switch (**nexthdr) { @@ -111,7 +112,10 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) + offset); - offset += ipv6_optlen(exthdr); + len = ipv6_optlen(exthdr); + if (len + offset >= IPV6_MAXPLEN) + return -EINVAL; + offset += len; *nexthdr = &exthdr->nexthdr; } |