From: Florian Westphal Date: Fri, 1 Apr 2016 12:17:27 +0000 (+0200) Subject: netfilter: x_tables: check standard target size too X-Git-Tag: v4.4.14-KARO~12 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;ds=sidebyside;h=2066499780e1455c43833b5b34858124047331ff;p=karo-tx-linux.git netfilter: x_tables: check standard target size too commit 7ed2abddd20cf8f6bd27f65bd218f26fa5bf7f44 upstream. We have targets and standard targets -- the latter carries a verdict. The ip/ip6tables validation functions will access t->verdict for the standard targets to fetch the jump offset or verdict for chainloop detection, but this happens before the targets get checked/validated. Thus we also need to check for verdict presence here, else t->verdict can point right after a blob. Spotted with UBSAN while testing malformed blobs. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index cfdb9591cf21..1f8cfe7379f7 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -539,6 +539,13 @@ int xt_compat_match_to_user(const struct xt_entry_match *m, } EXPORT_SYMBOL_GPL(xt_compat_match_to_user); +/* non-compat version may have padding after verdict */ +struct compat_xt_standard_target { + struct compat_xt_entry_target t; + compat_uint_t verdict; +}; + +/* see xt_check_entry_offsets */ int xt_compat_check_entry_offsets(const void *base, unsigned int target_offset, unsigned int next_offset) @@ -556,6 +563,10 @@ int xt_compat_check_entry_offsets(const void *base, if (target_offset + t->u.target_size > next_offset) return -EINVAL; + if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && + target_offset + sizeof(struct compat_xt_standard_target) != next_offset) + return -EINVAL; + return 0; } EXPORT_SYMBOL(xt_compat_check_entry_offsets); @@ -595,6 +606,10 @@ int xt_check_entry_offsets(const void *base, if (target_offset + t->u.target_size > next_offset) return -EINVAL; + if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && + target_offset + sizeof(struct xt_standard_target) != next_offset) + return -EINVAL; + return 0; } EXPORT_SYMBOL(xt_check_entry_offsets);