netfilter: x_tables: check for bogus target offset

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commit ce683e5f9d upstream.

We're currently asserting that targetoff + targetsize <= nextoff.

Extend it to also check that targetoff is >= sizeof(xt_entry).
Since this is generic code, add an argument pointing to the start of the
match/target, we can then derive the base structure size from the delta.

We also need the e->elems pointer in a followup change to validate matches.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Florian Westphal 2016-04-01 14:17:28 +02:00 • committed by Greg Kroah-Hartman

parent 2066499780

commit 8a86562154

5 changed files with 26 additions and 10 deletions

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4

include/linux/netfilter/x_tables.h

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5

net/ipv4/netfilter/arp_tables.c

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5

net/ipv4/netfilter/ip_tables.c

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5

net/ipv6/netfilter/ip6_tables.c

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17

net/netfilter/x_tables.c

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