From c5c56513b779cb082d05f63c606bde9321d395fb Mon Sep 17 00:00:00 2001 From: Sona Sarmadi Date: Tue, 22 Apr 2014 13:52:58 +0200 Subject: [PATCH] net: fib: fib6_add: fix potential NULL pointer dereference 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 Cc: Lin Ming Cc: Matti Vaittinen Cc: Hannes Frederic Sowa Acked-by: Hannes Frederic Sowa Acked-by: Matti Vaittinen Signed-off-by: David S. Miller Signed-off-by: Sona Sarmadi --- net/ipv6/ip6_fib.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 5fc9c7a..45562f6 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -828,6 +828,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info) if (IS_ERR(fn)) { err = PTR_ERR(fn); + fn = NULL; goto out; } -- 1.7.10.4