This is a note to let you know that I've just added the patch titled

netfilter: x_tables: make allocation less aggressive

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: netfilter-x_tables-make-allocation-less-aggressive.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 0537250fdc6c876ed4cbbe874c739aebef493ee2 Mon Sep 17 00:00:00 2001

From: Michal Hocko mhocko@kernel.org Date: Tue, 30 Jan 2018 11:30:11 -0800 Subject: netfilter: x_tables: make allocation less aggressive

From: Michal Hocko mhocko@kernel.org

commit 0537250fdc6c876ed4cbbe874c739aebef493ee2 upstream.

syzbot has noticed that xt_alloc_table_info can allocate a lot of memory. This is an admin only interface but an admin in a namespace is sufficient as well. eacd86ca3b03 ("net/netfilter/x_tables.c: use kvmalloc() in xt_alloc_table_info()") has changed the opencoded kmalloc->vmalloc fallback into kvmalloc. It has dropped __GFP_NORETRY on the way because vmalloc has simply never fully supported __GFP_NORETRY semantic. This is still the case because e.g. page tables backing the vmalloc area are hardcoded GFP_KERNEL.

Revert back to __GFP_NORETRY as a poors man defence against excessively large allocation request here. We will not rule out the OOM killer completely but __GFP_NORETRY should at least stop the large request in most cases.

[akpm@linux-foundation.org: coding-style fixes] Fixes: eacd86ca3b03 ("net/netfilter/x_tables.c: use kvmalloc() in xt_alloc_tableLink: http://lkml.kernel.org/r/20180130140104.GE21609@dhcp22.suse.cz Signed-off-by: Michal Hocko mhocko@suse.com Acked-by: Florian Westphal fw@strlen.de Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: David S. Miller davem@davemloft.net Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- net/netfilter/x_tables.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -1008,7 +1008,12 @@ struct xt_table_info *xt_alloc_table_inf if ((size >> PAGE_SHIFT) + 2 > totalram_pages) return NULL;

- info = kvmalloc(sz, GFP_KERNEL); + /* __GFP_NORETRY is not fully supported by kvmalloc but it should + * work reasonably well if sz is too large and bail out rather + * than shoot all processes down before realizing there is nothing + * more to reclaim. + */ + info = kvmalloc(sz, GFP_KERNEL | __GFP_NORETRY); if (!info) return NULL;

Patches currently in stable-queue which might be from mhocko@kernel.org are

queue-4.15/netfilter-x_tables-make-allocation-less-aggressive.patch