]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
net: fib6: fib6_commit_metrics: fix potential NULL pointer dereference
authorDaniel Borkmann <dborkman@redhat.com>
Mon, 5 Jan 2015 22:57:43 +0000 (23:57 +0100)
committerDavid S. Miller <davem@davemloft.net>
Tue, 6 Jan 2015 03:55:24 +0000 (22:55 -0500)
commit0409c9a5a7546043d32e8c46df0dcaf65f97f659
treed928884ae43414093c2f870bfb8206b65cdc9a30
parent6cb69742daa1770fe1ce54cf45f8951376518176
net: fib6: fib6_commit_metrics: fix potential NULL pointer dereference

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 <mkubecek@suse.cz>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv6/ip6_fib.c