From 0409c9a5a7546043d32e8c46df0dcaf65f97f659 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 5 Jan 2015 23:57:43 +0100 Subject: [PATCH] net: fib6: fib6_commit_metrics: fix potential NULL pointer dereference MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When IPv6 host routes with metrics attached are being added, we fetch the metrics store from the dst via COW through dst_metrics_write_ptr(), added through commit e5fd387ad5b3. One remaining problem here is that we actually call into inet_getpeer() and may end up allocating/creating a new peer from the kmemcache, which may fail. Example trace from perf probe (inet_getpeer:41) where create is 1: ip 6877 [002] 4221.391591: probe:inet_getpeer: (ffffffff8165e293) 85e294 inet_getpeer.part.7 (<- kmem_cache_alloc()) 85e578 inet_getpeer 8eb333 ipv6_cow_metrics 8f10ff fib6_commit_metrics Therefore, a check for NULL on the return of dst_metrics_write_ptr() is necessary here. Joint work with Florian Westphal. Fixes: e5fd387ad5b3 ("ipv6: do not overwrite inetpeer metrics prematurely") Cc: Michal Kubeček Signed-off-by: Florian Westphal Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- Reading git-format-patch failed