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authorAntoine Tenart <atenart@kernel.org>2020-12-23 22:23:20 +0100
committerJakub Kicinski <kuba@kernel.org>2020-12-28 13:26:46 -0800
commit1ad58225dba3f2f598d2c6daed4323f24547168f (patch)
treecab676a3988271507c52b78cb24d9dacd65d3f77
parent59b4a8fa27f5a895582ada1ae5034af7c94a57b5 (diff)
downloadlinux-1ad58225dba3f2f598d2c6daed4323f24547168f.tar.bz2
net-sysfs: take the rtnl lock when storing xps_cpus
Two race conditions can be triggered when storing xps cpus, resulting in various oops and invalid memory accesses: 1. Calling netdev_set_num_tc while netif_set_xps_queue: - netif_set_xps_queue uses dev->tc_num as one of the parameters to compute the size of new_dev_maps when allocating it. dev->tc_num is also used to access the map, and the compiler may generate code to retrieve this field multiple times in the function. - netdev_set_num_tc sets dev->tc_num. If new_dev_maps is allocated using dev->tc_num and then dev->tc_num is set to a higher value through netdev_set_num_tc, later accesses to new_dev_maps in netif_set_xps_queue could lead to accessing memory outside of new_dev_maps; triggering an oops. 2. Calling netif_set_xps_queue while netdev_set_num_tc is running: 2.1. netdev_set_num_tc starts by resetting the xps queues, dev->tc_num isn't updated yet. 2.2. netif_set_xps_queue is called, setting up the map with the *old* dev->num_tc. 2.3. netdev_set_num_tc updates dev->tc_num. 2.4. Later accesses to the map lead to out of bound accesses and oops. A similar issue can be found with netdev_reset_tc. One way of triggering this is to set an iface up (for which the driver uses netdev_set_num_tc in the open path, such as bnx2x) and writing to xps_cpus in a concurrent thread. With the right timing an oops is triggered. Both issues have the same fix: netif_set_xps_queue, netdev_set_num_tc and netdev_reset_tc should be mutually exclusive. We do that by taking the rtnl lock in xps_cpus_store. Fixes: 184c449f91fe ("net: Add support for XPS with QoS via traffic classes") Signed-off-by: Antoine Tenart <atenart@kernel.org> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--net/core/net-sysfs.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 999b70c59761..7cc15dec1717 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1396,7 +1396,13 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
return err;
}
+ if (!rtnl_trylock()) {
+ free_cpumask_var(mask);
+ return restart_syscall();
+ }
+
err = netif_set_xps_queue(dev, mask, index);
+ rtnl_unlock();
free_cpumask_var(mask);