netfilter: x_tables: fix compat match/target pad out-of-bound write

xt_compat_match/target_from_user doesn't check that zeroing the area
to start of next rule won't write past end of allocated ruleset blob.

Remove this code and zero the entire blob beforehand.

Reported-by: Andy Nguyen <>
Fixes: 9fa492cdc160c ("[NETFILTER]: x_tables: simplify compat API")
Signed-off-by: Florian Westphal <>
Signed-off-by: Pablo Neira Ayuso <>
4 files changed