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[PATCH 4.4 09/76] ipv4: provide stronger user input validation in nl_fib_input()

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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit c64c0b3cac4c5b8cb093727d2c19743ea3965c0b ]

Alexander reported a KMSAN splat caused by reads of uninitialized
field (tb_id_in) from user provided struct fib_result_nl

It turns out nl_fib_input() sanity tests on user input is a bit
wrong :

User can pretend nlh->nlmsg_len is big enough, but provide
at sendmsg() time a too small buffer.

Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/fib_frontend.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1080,7 +1080,8 @@ static void nl_fib_input(struct sk_buff
 
 	net = sock_net(skb->sk);
 	nlh = nlmsg_hdr(skb);
-	if (skb->len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len ||
+	if (skb->len < nlmsg_total_size(sizeof(*frn)) ||
+	    skb->len < nlh->nlmsg_len ||
 	    nlmsg_len(nlh) < sizeof(*frn))
 		return;
 

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[PATCH 4.4 00/76] 4.4.58-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:00 +0200
  [PATCH 4.4 06/76] net/mlx5: Increase number of max QPs in default profile Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:00 +0200
  [PATCH 4.4 13/76] Input: i8042 - add noloop quirk for Dell Embedded Box PC 3000 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:00 +0200
  [PATCH 4.4 19/76] Input: kbtab - validate number of endpoints before using them Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:00 +0200
  [PATCH 4.4 09/76] ipv4: provide stronger user input validation in nl_fib_input() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:00 +0200
  [PATCH 4.4 12/76] Input: elan_i2c - add ASUS EeeBook X205TA special touchpad fw Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:10 +0200
  [PATCH 4.4 17/76] Input: yealink - validate number of endpoints before using them Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-28 16:10 +0200
  Re: [PATCH 4.4 00/76] 4.4.58-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-03-28 21:40 +0200
  Re: [PATCH 4.4 00/76] 4.4.58-stable review Guenter Roeck <linux@roeck-us.net> - 2017-03-29 05:10 +0200

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