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Message-Id: <20150301.140051.1600529369087381519.davem@davemloft.net> Date: Sun, 01 Mar 2015 14:00:51 -0500 (EST) From: David Miller <davem@...emloft.net> To: arvid.brodin@...en.se Cc: netdev@...r.kernel.org, nicolas.dichtel@...nd.com Subject: Re: [PATCH v2 net] net/hsr: Fix NULL pointer dereference and refcnt bugs when deleting a HSR interface. From: Arvid Brodin <arvid.brodin@...en.se> Date: Fri, 27 Feb 2015 21:26:03 +0100 > To repeat: > > $ sudo ip link del hsr0 > BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 > IP: [<ffffffff8187f495>] hsr_del_port+0x15/0xa0 > etc... > > Bug description: > > As part of the hsr master device destruction, hsr_del_port() is called for each of > the hsr ports. At each such call, the master device is updated regarding features > and mtu. When the master device is freed before the slave interfaces, master will > be NULL in hsr_del_port(), which led to a NULL pointer dereference. > > Additionally, dev_put() was called on the master device itself in hsr_del_port(), > causing a refcnt error. > > A third bug in the same code path was that the rtnl lock was not taken before > hsr_del_port() was called as part of hsr_dev_destroy(). > > The reporter (Nicolas Dichtel) also said: "hsr_netdev_notify() supposes that the > port will always be available when the notification is for an hsr interface. It's > wrong. For example, netdev_wait_allrefs() may resend NETDEV_UNREGISTER.". As a > precaution against this, a check for port == NULL was added in hsr_dev_notify(). > > Reported-by: Nicolas Dichtel <nicolas.dichtel@...nd.com> > Fixes: 51f3c605318b056a ("net/hsr: Move slave init to hsr_slave.c.") > Signed-off-by: Arvid Brodin <arvid.brodin@...en.se> Applied. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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