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Date: Fri, 11 Oct 2013 12:37:49 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Daniel Borkmann <dborkman@...hat.com>, Lin Ming <mlin@...pku.edu.cn>, Matti Vaittinen <matti.vaittinen@....com>, Hannes Frederic Sowa <hannes@...essinduktion.org>, "David S. Miller" <davem@...emloft.net> Subject: [ 009/110] net: fib: fib6_add: fix potential NULL pointer dereference 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann <dborkman@...hat.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@...hat.com> Cc: Lin Ming <mlin@...pku.edu.cn> Cc: Matti Vaittinen <matti.vaittinen@....com> Cc: Hannes Frederic Sowa <hannes@...essinduktion.org> Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org> Acked-by: Matti Vaittinen <matti.vaittinen@....com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- net/ipv6/ip6_fib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -825,9 +825,9 @@ int fib6_add(struct fib6_node *root, str 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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