linux-kernel - [099/205] ethtool: Fix potential kernel buffer overflow in ETHTOOL

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Date:	Fri, 30 Jul 2010 10:51:56 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Ben Hutchings <bhutchings@...arflare.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [099/205] ethtool: Fix potential kernel buffer overflow in ETHTOOL_GRXCLSRLALL

2.6.34-stable review patch.  If anyone has any objections, please let us know.

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

From: Ben Hutchings <bhutchings@...arflare.com>

commit db048b69037e7fa6a7d9e95a1271a50dc08ae233 upstream.

On a 32-bit machine, info.rule_cnt >= 0x40000000 leads to integer
overflow and the buffer may be smaller than needed.  Since
ETHTOOL_GRXCLSRLALL is unprivileged, this can presumably be used for at
least denial of service.

Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 net/core/ethtool.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -328,8 +328,9 @@ static noinline_for_stack int ethtool_ge
 
 	if (info.cmd == ETHTOOL_GRXCLSRLALL) {
 		if (info.rule_cnt > 0) {
-			rule_buf = kmalloc(info.rule_cnt * sizeof(u32),
-					   GFP_USER);
+			if (info.rule_cnt <= KMALLOC_MAX_SIZE / sizeof(u32))
+				rule_buf = kmalloc(info.rule_cnt * sizeof(u32),
+						   GFP_USER);
 			if (!rule_buf)
 				return -ENOMEM;
 		}


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