[PATCH 6.19 117/342] iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

Greg Kroah-Hartman
2026-03-31T16:36:19Z

From: Kohei Enju <kohei@enjuk.jp>

[ Upstream commit fecacfc95f195b99c71c579a472120d0b4ed65fa ]

iavf incorrectly uses real_num_tx_queues for ETH_SS_STATS. Since the
value could change in runtime, we should use num_tx_queues instead.

Moreover iavf_get_ethtool_stats() uses num_active_queues while
iavf_get_sset_count() and iavf_get_stat_strings() use
real_num_tx_queues, which triggers out-of-bounds writes when we do
"ethtool -L" and "ethtool -S" simultaneously [1].

For example when we change channels from 1 to 8, Thread 3 could be
scheduled before Thread 2, and out-of-bounds writes could be triggered
in Thread 3:

Thread 1 (ethtool -L) Thread 2 (work) Thread 3 (ethtool -S)
iavf_set_channels()
...
iavf_alloc_queues()
-> num_active_queues = 8
iavf_schedule_finish_config()
iavf_get_sset_count()
real_num_tx_queues: 1
-> buffer for 1 queue
iavf_get_ethtool_stats()
num_active_queues: 8
-> out-of-bounds!
iavf_finish_config()
-> real_num_tx_queues = 8

Use immutable num_tx_queues in all related functions to avoid the issue.

[1]
BUG: KASAN: vmalloc-out-of-bounds in iavf_add_one_ethtool_stat+0x200/0x270
Write of size 8 at addr ffffc900031c9080 by task ethtool/5800

CPU: 1 UID: 0 PID: 5800 Comm: ethtool Not tainted 6.19.0-enjuk-08403-g8137e3db7f1c #241 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x6f/0xb0
print_report+0x170/0x4f3
kasan_report+0xe1/0x180
iavf_add_one_ethtool_stat+0x200/0x270
iavf_get_ethtool_stats+0x14c/0x2e0
__dev_ethtool+0x3d0c/0x5830
dev_ethtool+0x12d/0x270
dev_ioctl+0x53c/0xe30
sock_do_ioctl+0x1a9/0x270
sock_ioctl+0x3d4/0x5e0
__x64_sys_ioctl+0x137/0x1c0
do_syscall_64+0xf3/0x690
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7da0e6e36d
...
</TASK>

The buggy address belongs to a 1-page vmalloc region starting at 0xffffc900031c9000 allocated at __dev_ethtool+0x3cc9/0x5830
The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000
index:0xffff88813a013de0 pfn:0x13a013
flags: 0x200000000000000(node=0|zone=2)
raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff88813a013de0 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffffc900031c8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc900031c9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900031c9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
^
ffffc900031c9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
ffffc900031c9180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8

Fixes: 64430f70ba6f ("iavf: Fix displaying queue statistics shown by ethtool")
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../net/ethernet/intel/iavf/iavf_ethtool.c | 31 +++++++++----------
1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
index 6ff3842a1ff1f..98bec3afc2006 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
@@ -313,14 +313,13 @@ static int iavf_get_sset_count(struct net_device *netdev, int sset)
{
/* Report the maximum number queues, even if not every queue is
* currently configured. Since allocation of queues is in pairs,
- * use netdev->real_num_tx_queues * 2. The real_num_tx_queues is set
- * at device creation and never changes.
+ * use netdev->num_tx_queues * 2. The num_tx_queues is set at
+ * device creation and never changes.
*/

if (sset == ETH_SS_STATS)
return IAVF_STATS_LEN +
- (IAVF_QUEUE_STATS_LEN * 2 *
- netdev->real_num_tx_queues);
+ (IAVF_QUEUE_STATS_LEN * 2 * netdev->num_tx_queues);
else
return -EINVAL;
}
@@ -345,19 +344,19 @@ static void iavf_get_ethtool_stats(struct net_device *netdev,
iavf_add_ethtool_stats(&data, adapter, iavf_gstrings_stats);

rcu_read_lock();
- /* As num_active_queues describe both tx and rx queues, we can use
- * it to iterate over rings' stats.
+ /* Use num_tx_queues to report stats for the maximum number of queues.
+ * Queues beyond num_active_queues will report zero.
*/
- for (i = 0; i < adapter->num_active_queues; i++) {
- struct iavf_ring *ring;
+ for (i = 0; i < netdev->num_tx_queues; i++) {
+ struct iavf_ring *tx_ring = NULL, *rx_ring = NULL;

- /* Tx rings stats */
- ring = &adapter->tx_rings[i];
- iavf_add_queue_stats(&data, ring);
+ if (i < adapter->num_active_queues) {
+ tx_ring = &adapter->tx_rings[i];
+ rx_ring = &adapter->rx_rings[i];
+ }

- /* Rx rings stats */
- ring = &adapter->rx_rings[i];
- iavf_add_queue_stats(&data, ring);
+ iavf_add_queue_stats(&data, tx_ring);
+ iavf_add_queue_stats(&data, rx_ring);
}
rcu_read_unlock();
}
@@ -376,9 +375,9 @@ static void iavf_get_stat_strings(struct net_device *netdev, u8 *data)
iavf_add_stat_strings(&data, iavf_gstrings_stats);

/* Queues are always allocated in pairs, so we just use
- * real_num_tx_queues for both Tx and Rx queues.
+ * num_tx_queues for both Tx and Rx queues.
*/
- for (i = 0; i < netdev->real_num_tx_queues; i++) {
+ for (i = 0; i < netdev->num_tx_queues; i++) {
iavf_add_stat_strings(&data, iavf_gstrings_queue_stats,
"tx", i);
iavf_add_stat_strings(&data, iavf_gstrings_queue_stats,
--
2.51.0