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| author | Daniel Borkmann <dborkman@redhat.com> | 2015-01-05 23:57:43 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-01-05 22:55:24 -0500 |
| commit | 0409c9a5a7546043d32e8c46df0dcaf65f97f659 (patch) | |
| tree | d928884ae43414093c2f870bfb8206b65cdc9a30 /net/ipv6 | |
| parent | 6cb69742daa1770fe1ce54cf45f8951376518176 (diff) | |
| download | linux-0409c9a5a7546043d32e8c46df0dcaf65f97f659.tar.gz linux-0409c9a5a7546043d32e8c46df0dcaf65f97f659.tar.bz2 linux-0409c9a5a7546043d32e8c46df0dcaf65f97f659.zip | |
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>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/ip6_fib.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index b2d1838897c9..db4984e13f2f 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -633,18 +633,17 @@ static bool rt6_qualify_for_ecmp(struct rt6_info *rt) static int fib6_commit_metrics(struct dst_entry *dst, struct nlattr *mx, int mx_len) { + bool dst_host = dst->flags & DST_HOST; struct nlattr *nla; int remaining; u32 *mp; - if (dst->flags & DST_HOST) { - mp = dst_metrics_write_ptr(dst); - } else { - mp = kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC); - if (!mp) - return -ENOMEM; + mp = dst_host ? dst_metrics_write_ptr(dst) : + kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC); + if (unlikely(!mp)) + return -ENOMEM; + if (!dst_host) dst_init_metrics(dst, mp, 0); - } nla_for_each_attr(nla, mx, mx_len, remaining) { int type = nla_type(nla); |