lkml.org 
[lkml]   [2013]   [Oct]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.8 31/81] net: fib: fib6_add: fix potential NULL pointer dereference
Date
3.8.13.12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Borkmann <dborkman@redhat.com>

[ Upstream commit ae7b4e1f213aa659aedf9c6ecad0bf5f0476e1e2 ]

When the kernel is compiled with CONFIG_IPV6_SUBTREES, and we return
with an error in fn = fib6_add_1(), then error codes are encoded into
the return pointer e.g. ERR_PTR(-ENOENT). In such an error case, we
write the error code into err and jump to out, hence enter the if(err)
condition. Now, if CONFIG_IPV6_SUBTREES is enabled, we check for:

if (pn != fn && pn->leaf == rt)
...
if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO))
...

Since pn is NULL and fn is f.e. ERR_PTR(-ENOENT), then pn != fn
evaluates to true and causes a NULL-pointer dereference on further
checks on pn. Fix it, by setting both NULL in error case, so that
pn != fn already evaluates to false and no further dereference
takes place.

This was first correctly implemented in 4a287eba2 ("IPv6 routing,
NLM_F_* flag support: REPLACE and EXCL flags support, warn about
missing CREATE flag"), but the bug got later on introduced by
188c517a0 ("ipv6: return errno pointers consistently for fib6_add_1()").

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Lin Ming <mlin@ss.pku.edu.cn>
Cc: Matti Vaittinen <matti.vaittinen@nsn.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Matti Vaittinen <matti.vaittinen@nsn.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
net/ipv6/ip6_fib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 7c39aa6..b3adb7f 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -827,9 +827,9 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info)
fn = fib6_add_1(root, &rt->rt6i_dst.addr, sizeof(struct in6_addr),
rt->rt6i_dst.plen, offsetof(struct rt6_info, rt6i_dst),
allow_create, replace_required);
-
if (IS_ERR(fn)) {
err = PTR_ERR(fn);
+ fn = NULL;
goto out;
}

--
1.8.1.2


\
 
 \ /
  Last update: 2013-10-29 19:41    [W:0.243 / U:18.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site