[11/30] netfilter: x_tables: cap allocations at 512 mbyte

Message ID 20180312175920.9022-12-pablo@netfilter.org
State Changes Requested
Delegated to: Pablo Neira
Headers show
Series
  • [01/30] netfilter: nf_tables: nf_tables_obj_lookup_byhandle() can be static
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Commit Message

Pablo Neira Ayuso March 12, 2018, 5:59 p.m.
From: Florian Westphal <fw@strlen.de>

Arbitrary limit, however, this still allows huge rulesets
(> 1 million rules).  This helps with automated fuzzer as it prevents
oom-killer invocation.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/x_tables.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 4e6cbb38e616..dc68ac49614a 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -40,6 +40,7 @@  MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
 
 #define XT_PCPU_BLOCK_SIZE 4096
+#define XT_MAX_TABLE_SIZE	(512 * 1024 * 1024)
 
 struct compat_delta {
 	unsigned int offset; /* offset in kernel */
@@ -1117,7 +1118,7 @@  struct xt_table_info *xt_alloc_table_info(unsigned int size)
 	struct xt_table_info *info = NULL;
 	size_t sz = sizeof(*info) + size;
 
-	if (sz < sizeof(*info))
+	if (sz < sizeof(*info) || sz >= XT_MAX_TABLE_SIZE)
 		return NULL;
 
 	/* __GFP_NORETRY is not fully supported by kvmalloc but it should