netconsole: avoid null pointer dereference at show_local_mac()

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To: <git-commits-head@...>
Date: Friday, February 15, 2008 - 6:01 pm

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=69c368...
Commit:     69c3683ca7fe066ecba9e8a0424c5abd258a5d58
Parent:     b5c15fc004ac83b7ad280acbe0fd4bbed7e2c8d4
Author:     Keiichi KII <k-keiichi@bx.jp.nec.com>
AuthorDate: Fri Feb 15 02:01:58 2008 -0800
Committer:  David S. Miller <davem@davemloft.net>
CommitDate: Fri Feb 15 02:01:58 2008 -0800

    netconsole: avoid null pointer dereference at show_local_mac()
    
    This patch avoids a null pointer dereference when we read local_mac
    for netconsole in configfs and shows default local mac address
    value.
    
    A null pointer dereference occurs when we call show_local_mac() via
    local_mac entry in configfs before we setup the content of netpoll
    using netpoll_setup().
    
    Signed-off-by: Keiichi KII <k-keiichi@bx.jp.nec.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/netconsole.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 31e047d..501e451 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -309,8 +309,8 @@ static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 	struct net_device *dev = nt->np.dev;
 
 	DECLARE_MAC_BUF(mac);
-	return snprintf(buf, PAGE_SIZE, "%s\n",
-			print_mac(mac, dev->dev_addr));
+	return snprintf(buf, PAGE_SIZE, "%s\n", dev ?
+			print_mac(mac, dev->dev_addr) : "ff:ff:ff:ff:ff:ff");
 }
 
 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
-
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netconsole: avoid null pointer dereference at show_local_mac(), Linux Kernel Mailing List..., (Fri Feb 15, 6:01 pm)