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authorMichal Hocko <mhocko@kernel.org>2018-01-30 11:30:11 -0800
committerPablo Neira Ayuso <pablo@netfilter.org>2018-02-02 12:45:16 +0100
commit0537250fdc6c876ed4cbbe874c739aebef493ee2 (patch)
tree849e9a9c317dcbb325eda7d8a81bc3615f473470 /net
parent743ffffefac1c670c6618742c923f6275d819604 (diff)
downloadlinux-0537250fdc6c876ed4cbbe874c739aebef493ee2.tar.bz2
netfilter: x_tables: make allocation less aggressive
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>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/x_tables.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 8fa4d37141a7..2f685ee1f9c8 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1008,7 +1008,12 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size)
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;