Commit 6ff8315a authored May 14, 2016 by Linus Torvalds Committed by Greg Kroah-Hartman May 18, 2016

nf_conntrack: avoid kernel pointer value leak in slab name



commit 31b0b385f69d8d5491a4bca288e25e63f1d945d0 upstream.

The slab name ends up being visible in the directory structure under
/sys, and even if you don't have access rights to the file you can see
the filenames.

Just use a 64-bit counter instead of the pointer to the 'net' structure
to generate a unique name.

This code will go away in 4.7 when the conntrack code moves to a single
kmemcache, but this is the backportable simple solution to avoiding
leaking kernel pointers to user space.

Fixes: 5b3501fa ("netfilter: nf_conntrack: per netns nf_conntrack_cachep")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 62b68367

net/netfilter/nf_conntrack_core.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1757,6 +1757,7 @@ void nf_conntrack_init_end(void)

		int nf_conntrack_init_net(struct net *net)
		{
		static atomic64_t unique_id;
		int ret = -ENOMEM;
		int cpu;

		@@ -1779,7 +1780,8 @@ int nf_conntrack_init_net(struct net *net)
		if (!net->ct.stat)
		goto err_pcpu_lists;

		net->ct.slabname = kasprintf(GFP_KERNEL, "nf_conntrack_%p", net);
		net->ct.slabname = kasprintf(GFP_KERNEL, "nf_conntrack_%llu",
		(u64)atomic64_inc_return(&unique_id));
		if (!net->ct.slabname)
		goto err_slabname;