netdev - [PATCH] net: cxgb4: avoid memcpy beyond end of source buffer

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Message-Id: <20180202151849.808610-1-arnd@arndb.de>
Date:   Fri,  2 Feb 2018 16:18:37 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Ganesh Goudar <ganeshgr@...lsio.com>
Cc:     Nicolas Pitre <nico@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Rahul Lakkireddy <rahul.lakkireddy@...lsio.com>,
        Kumar Sanghvi <kumaras@...lsio.com>,
        Harsh Jain <harsh@...lsio.com>,
        Atul Gupta <atul.gupta@...lsio.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] net: cxgb4: avoid memcpy beyond end of source buffer

Building with link-time-optimizations revealed that the cxgb4 driver does
a fixed-size memcpy() from a variable-length constant string into the
network interface name:

In function 'memcpy',
    inlined from 'cfg_queues_uld.constprop' at drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.c:335:2,
    inlined from 'cxgb4_register_uld.constprop' at drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.c:719:9:
include/linux/string.h:350:3: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter
   __read_overflow2();
   ^

I can see two equally workable solutions: either we use a strncpy() instead
of the memcpy() to stop at the end of the input, or we make the source buffer
fixed length as well. This implements the latter.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h
index 1d37672902da..a14e8db51cdc 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h
@@ -355,7 +355,7 @@ struct cxgb4_lld_info {
 };
 
 struct cxgb4_uld_info {
-	const char *name;
+	char name[IFNAMSIZ];
 	void *handle;
 	unsigned int nrxq;
 	unsigned int rxq_size;
-- 
2.9.0