netfilter: x_tables: make allocation less aggressive
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Web: https://git.kernel.org/torvalds/c/0537250fdc6c876ed4cbbe874c739aebef493ee2 Commit: 0537250fdc6c876ed4cbbe874c739aebef493ee2 Parent: 743ffffefac1c670c6618742c923f6275d819604 Refname: refs/heads/master Author: Michal Hocko <[email protected]> AuthorDate: Tue Jan 30 11:30:11 2018 -0800 Committer: Pablo Neira Ayuso <[email protected]> CommitDate: Fri Feb 2 12:45:16 2018 +0100 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. [[email protected]: coding-style fixes] Fixes: eacd86ca3b03 ("net/netfilter/x_tables.c: use kvmalloc() in xt_alloc_tableLink: http://lkml.kernel.org/r/[email protected] Signed-off-by: Michal Hocko <[email protected]> Acked-by: Florian Westphal <[email protected]> Reviewed-by: Andrew Morton <[email protected]> Cc: David S. Miller <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> --- net/netfilter/x_tables.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) 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; -- To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html