| 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; |
| |
