Re: "WARNING in nf_ct_alloc_hashtable" in Linux kernel version 6.13.0-rc2

[Pablo Neira Ayuso <pablo@netfilter.org>]

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Hi,

On Fri, Jan 03, 2025 at 06:01:50PM -0800, Andrew Morton wrote:
> On Fri, 3 Jan 2025 17:12:53 +0800 cheung wall <zzqq0103.hey@gmail.com> wrote:
> 
> > Hello,
> > 
> > I am writing to report a potential vulnerability identified in the
> > Linux Kernel version 6.13.0-rc2. This issue was discovered using our
> > custom vulnerability discovery tool.
> > 
> > HEAD commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4 (tag: v6.13-rc2)
> > 
> > Affected File: mm/util.c
> > 
> > File: mm/util.c
> > 
> > Function: __kvmalloc_node_noprof
> 
> (cc netfilter-devel)
> 
> This is
> 
> 	/* Don't even allow crazy sizes */
> 	if (unlikely(size > INT_MAX)) {
> 		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> 		return NULL;
> 	}
> 
> in __kvmalloc_node_noprof().

Ok, then I assume this is a WARN_ON_ONCE splat.

I'm attaching a patch to address this.

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diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 8666d733b984..13a2097b56e2 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2516,7 +2516,7 @@ void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
 	BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
 	nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
 
-	hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL);
+	hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL | __GFP_NOWARN);
 
 	if (hash && nulls)
 		for (i = 0; i < nr_slots; i++)