| From | Willy Tarreau <> | Subject | [PATCH 3.10 015/180] netfilter: x_tables: don't reject valid target size on some architectures | Date | Sun, 21 Aug 2016 17:29:05 +0200 |
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From: Florian Westphal <fw@strlen.de>
commit 7b7eba0f3515fca3296b8881d583f7c1042f5226 upstream.
Quoting John Stultz: In updating a 32bit arm device from 4.6 to Linus' current HEAD, I noticed I was having some trouble with networking, and realized that /proc/net/ip_tables_names was suddenly empty. Digging through the registration process, it seems we're catching on the:
if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && target_offset + sizeof(struct xt_standard_target) != next_offset) return -EINVAL;
Where next_offset seems to be 4 bytes larger then the offset + standard_target struct size.
next_offset needs to be aligned via XT_ALIGN (so we can access all members of ip(6)t_entry struct).
This problem didn't show up on i686 as it only needs 4-byte alignment for u64, but iptables userspace on other 32bit arches does insert extra padding.
Reported-by: John Stultz <john.stultz@linaro.org> Tested-by: John Stultz <john.stultz@linaro.org> Fixes: 7ed2abddd20cf ("netfilter: x_tables: check standard target size too") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Willy Tarreau <w@1wt.eu> --- net/netfilter/x_tables.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index c482633..6ac9fb4 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -628,7 +628,7 @@ int xt_compat_check_entry_offsets(const void *base, const char *elems, return -EINVAL; if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && - target_offset + sizeof(struct compat_xt_standard_target) != next_offset) + COMPAT_XT_ALIGN(target_offset + sizeof(struct compat_xt_standard_target)) != next_offset) return -EINVAL; /* compat_xt_entry match has less strict aligment requirements, @@ -710,7 +710,7 @@ int xt_check_entry_offsets(const void *base, return -EINVAL; if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && - target_offset + sizeof(struct xt_standard_target) != next_offset) + XT_ALIGN(target_offset + sizeof(struct xt_standard_target)) != next_offset) return -EINVAL; return xt_check_entry_match(elems, base + target_offset, -- 2.8.0.rc2.1.gbe9624a
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