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authorAntoine Tenart <atenart@kernel.org>2020-12-23 22:23:22 +0100
committerJakub Kicinski <kuba@kernel.org>2020-12-28 13:26:46 -0800
commit2d57b4f142e0b03e854612b8e28978935414bced (patch)
tree81a1ff0915f1cfdc6883e2992f3908123fcb4f9e /net
parentfb25038586d0064123e393cadf1fadd70a9df97a (diff)
net-sysfs: take the rtnl lock when storing xps_rxqs
Two race conditions can be triggered when storing xps rxqs, 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_rxqs 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_rxqs_store. Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue") Signed-off-by: Antoine Tenart <atenart@kernel.org> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/net-sysfs.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 65886bfbf822..62ca2f2c0ee6 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1499,10 +1499,17 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
return err;
}
+ if (!rtnl_trylock()) {
+ bitmap_free(mask);
+ return restart_syscall();
+ }
+
cpus_read_lock();
err = __netif_set_xps_queue(dev, mask, index, true);
cpus_read_unlock();
+ rtnl_unlock();
+
bitmap_free(mask);
return err ? : len;
}