diff options
author | Antoine Tenart <atenart@kernel.org> | 2020-12-23 22:23:20 +0100 |
---|---|---|
committer | Jakub Kicinski <kuba@kernel.org> | 2020-12-28 13:26:46 -0800 |
commit | 1ad58225dba3f2f598d2c6daed4323f24547168f (patch) | |
tree | cab676a3988271507c52b78cb24d9dacd65d3f77 /net/core | |
parent | 59b4a8fa27f5a895582ada1ae5034af7c94a57b5 (diff) | |
download | linux-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>
Diffstat (limited to 'net/core')
-rw-r--r-- | net/core/net-sysfs.c | 6 |
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); |