[PATCH 4.4 72/75] netfilter: x_tables: check standard target size too
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-06-22 22:42:15
Also in:
lkml
4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal <fw@strlen.de> 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 <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/netfilter/x_tables.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c@@ -539,6 +539,13 @@ int xt_compat_match_to_user(const struct } 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 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 *b 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);