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authorEric Dumazet <edumazet@google.com>2018-07-30 20:09:11 -0700
committerDavid S. Miller <davem@davemloft.net>2018-07-31 14:41:29 -0700
commit56e2c94f055d328f5f6b0a5c1721cca2f2d4e0a1 (patch)
tree29f521556a514eab6c303d3974bf0b1773858fac
parente39eb599998ac4d8721af23f7da8710950a07823 (diff)
download96b-common-56e2c94f055d328f5f6b0a5c1721cca2f2d4e0a1.tar.gz
inet: frag: enforce memory limits earlier
We currently check current frags memory usage only when a new frag queue is created. This allows attackers to first consume the memory budget (default : 4 MB) creating thousands of frag queues, then sending tiny skbs to exceed high_thresh limit by 2 to 3 order of magnitude. Note that before commit 648700f76b03 ("inet: frags: use rhashtables for reassembly units"), work queue could be starved under DOS, getting no cpu cycles. After commit 648700f76b03, only the per frag queue timer can eventually remove an incomplete frag queue and its skbs. Fixes: b13d3cbfb8e8 ("inet: frag: move eviction of queues to work queue") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Jann Horn <jannh@google.com> Cc: Florian Westphal <fw@strlen.de> Cc: Peter Oskolkov <posk@google.com> Cc: Paolo Abeni <pabeni@redhat.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/inet_fragment.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 1e4cf3ab560f..0d70608cc2e1 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -157,9 +157,6 @@ static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
{
struct inet_frag_queue *q;
- if (!nf->high_thresh || frag_mem_limit(nf) > nf->high_thresh)
- return NULL;
-
q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
if (!q)
return NULL;
@@ -204,6 +201,9 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, void *key)
{
struct inet_frag_queue *fq;
+ if (!nf->high_thresh || frag_mem_limit(nf) > nf->high_thresh)
+ return NULL;
+
rcu_read_lock();
fq = rhashtable_lookup(&nf->rhashtable, key, nf->f->rhash_params);