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netfilter: synproxy: Fix out of bounds when parsing TCP options
[ Upstream commit5fc177ab75
] The TCP option parser in synproxy (synproxy_parse_options) could read one byte out of bounds. When the length is 1, the execution flow gets into the loop, reads one byte of the opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds the length of 1. This fix is inspired by commit9609dad263
("ipv4: tcp_input: fix stack out of bounds when parsing TCP options."). v2 changes: Added an early return when length < 0 to avoid calling skb_header_pointer with negative length. Cc: Young Xiao <92siuyang@gmail.com> Fixes:48b1de4c11
("netfilter: add SYNPROXY core/target") Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
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1 changed files with 5 additions and 0 deletions
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@ -31,6 +31,9 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
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int length = (th->doff * 4) - sizeof(*th);
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int length = (th->doff * 4) - sizeof(*th);
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u8 buf[40], *ptr;
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u8 buf[40], *ptr;
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if (unlikely(length < 0))
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return false;
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ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
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ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
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if (ptr == NULL)
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if (ptr == NULL)
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return false;
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return false;
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@ -47,6 +50,8 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
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length--;
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length--;
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continue;
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continue;
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default:
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default:
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if (length < 2)
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return true;
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opsize = *ptr++;
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opsize = *ptr++;
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if (opsize < 2)
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if (opsize < 2)
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return true;
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return true;
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