From 4ab42d78e37a294ac7bc56901d563c642e03c4ae Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 1 Nov 2015 16:22:53 +0000
Subject: ppp, slip: Validate VJ compression slot parameters completely
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Currently slhc_init() treats out-of-range values of rslots and tslots
as equivalent to 0, except that if tslots is too large it will
dereference a null pointer (CVE-2015-7799).

Add a range-check at the top of the function and make it return an
ERR_PTR() on error instead of NULL.  Change the callers accordingly.

Compile-tested only.

Reported-by: 郭永刚 <guoyonggang@360.cn>
References: http://article.gmane.org/gmane.comp.security.oss.general/17908
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/ppp/ppp_generic.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

(limited to 'drivers/net/ppp')

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index ed00446759b2..9a863c6a6a33 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -721,10 +721,8 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			val &= 0xffff;
 		}
 		vj = slhc_init(val2+1, val+1);
-		if (!vj) {
-			netdev_err(ppp->dev,
-				   "PPP: no memory (VJ compressor)\n");
-			err = -ENOMEM;
+		if (IS_ERR(vj)) {
+			err = PTR_ERR(vj);
 			break;
 		}
 		ppp_lock(ppp);
-- 
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