| Message ID | 1464739484-7817-1-git-send-email-fw@strlen.de |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
On Wed, Jun 01, 2016 at 02:04:44AM +0200, Florian Westphal wrote: > 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. Applied, thanks Florian. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index c69c892..2675d58 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -612,7 +612,7 @@ 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, @@ -694,7 +694,7 @@ 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,
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> --- net/netfilter/x_tables.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)