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nf_conntrack: avoid kernel pointer value leak in slab name

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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: 5b3501faa8 ("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>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Linus Torvalds 2016-05-14 11:11:44 -07:00 committed by David S. Miller
parent b915065862
commit 31b0b385f6
1 changed files with 3 additions and 1 deletions
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4
net/netfilter/nf_conntrack_core.c
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@ -1778,6 +1778,7 @@ void nf_conntrack_init_end(void)
int nf_conntrack_init_net(struct net *net)
{
static atomic64_t unique_id;
int ret = -ENOMEM;
int cpu;
@ -1800,7 +1801,8 @@ 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;