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tcp: md5: use kmalloc() backed scratch areas

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Some arches have virtually mapped kernel stacks, or will soon have.

tcp_md5_hash_header() uses an automatic variable to copy tcp header
before mangling th->check and calling crypto function, which might
be problematic on such arches.

David says that using percpu storage is also problematic on non SMP
builds.

Just use kmalloc() to allocate scratch areas.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2016-06-27 18:51:53 +02:00
committed by David S. Miller
parent 435c556cde
commit 19689e38ec
4 changed files with 41 additions and 32 deletions
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10
net/ipv4/tcp.c
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@@ -3026,8 +3026,18 @@ static void __tcp_alloc_md5sig_pool(void)
return;
for_each_possible_cpu(cpu) {
void *scratch = per_cpu(tcp_md5sig_pool, cpu).scratch;
struct ahash_request *req;
if (!scratch) {
scratch = kmalloc_node(sizeof(union tcp_md5sum_block) +
sizeof(struct tcphdr),
GFP_KERNEL,
cpu_to_node(cpu));
if (!scratch)
return;
per_cpu(tcp_md5sig_pool, cpu).scratch = scratch;
}
if (per_cpu(tcp_md5sig_pool, cpu).md5_req)
continue;