iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()
CVE-2026-31505 · published 22 Apr 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-31505?
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Who is affected
- Linux Linux: 64430f70ba6fcd5872ac190f4ae3ddee3f48f00d to < d5dcca707f56c46582486d783c1eca2323189111, 64430f70ba6fcd5872ac190f4ae3ddee3f48f00d to < 1f931dee5b726df1940348ec31614d64bac03aa6, 64430f70ba6fcd5872ac190f4ae3ddee3f48f00d to < bb85741d2dc2be207353a412f51b83697fcbefcf, 64430f70ba6fcd5872ac190f4ae3ddee3f48f00d to < fdf902bf86a80bf15792a1d20a67a5302498d7f1
- Linux Linux: 5.17
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
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- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()
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
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References
- git.kernel.org/stable/c/d5dcca707f56c46582486d783c1eca2323189111
- git.kernel.org/stable/c/1f931dee5b726df1940348ec31614d64bac03aa6
- git.kernel.org/stable/c/bb85741d2dc2be207353a412f51b83697fcbefcf
- git.kernel.org/stable/c/fdf902bf86a80bf15792a1d20a67a5302498d7f1
- git.kernel.org/stable/c/fecacfc95f195b99c71c579a472120d0b4ed65fa
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON