Out-of-bounds Write Affecting kernel-rt-debug-devel package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-devel package and not the kernel-rt-debug-devel package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

iavf: fix off-by-one issues in iavf_config_rss_reg()

There are off-by-one bugs when configuring RSS hash key and lookup table, causing out-of-bounds reads to memory [1] and out-of-bounds writes to device registers.

Before commit 43a3d9ba34c9 ("i40evf: Allow PF driver to configure RSS"), the loop upper bounds were: i <= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX which is safe since the value is the last valid index.

That commit changed the bounds to: i <= adapter->rss_{key,lut}_size / 4 where rss_{key,lut}_size / 4 is the number of dwords, so the last valid index is (rss_{key,lut}_size / 4) - 1. Therefore, using <= accesses one element past the end.

Fix the issues by using < instead of <=, ensuring we do not exceed the bounds.

[1] KASAN splat about rss_key_size off-by-one BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800 Read of size 4 at addr ffff888102c50134 by task kworker/u8:6/63

CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 Not tainted 6.18.0-rc2-enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: iavf iavf_watchdog_task Call Trace: <TASK> dump_stack_lvl+0x6f/0xb0 print_report+0x170/0x4f3 kasan_report+0xe1/0x1a0 iavf_config_rss+0x619/0x800 iavf_watchdog_task+0x2be7/0x3230 process_one_work+0x7fd/0x1420 worker_thread+0x4d1/0xd40 kthread+0x344/0x660 ret_from_fork+0x249/0x320 ret_from_fork_asm+0x1a/0x30 </TASK>

Allocated by task 63: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 __kmalloc_noprof+0x246/0x6f0 iavf_watchdog_task+0x28fc/0x3230 process_one_work+0x7fd/0x1420 worker_thread+0x4d1/0xd40 kthread+0x344/0x660 ret_from_fork+0x249/0x320 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff888102c50100 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes to the right of allocated 52-byte region [ffff888102c50100, ffff888102c50134)

The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102c50 flags: 0x200000000000000(node=0|zone=2) page_type: f5(slab) raw: 0200000000000000 ffff8881000418c0 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080200020 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff888102c50000: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc ffff888102c50080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc >ffff888102c50100: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc ^ ffff888102c50180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff888102c50200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

• https://bugzilla.redhat.com/show_bug.cgi?id=2429052
• https://access.redhat.com/security/cve/CVE-2025-71087
• https://git.kernel.org/stable/c/18de0e41d69d97fab10b91fecf10ae78a5e43232
• https://git.kernel.org/stable/c/3095228e1320371e143835d0cebeef1a8a754c66
• https://git.kernel.org/stable/c/6daa2893f323981c7894c68440823326e93a7d61
• https://git.kernel.org/stable/c/d7369dc8dd7cbf5cee3a22610028d847b6f02982
• https://git.kernel.org/stable/c/f36de3045d006e6d9be1be495f2ed88d1721e752
• https://git.kernel.org/stable/c/5bb18bfd505ca1affbca921462c350095a6c798c
• https://git.kernel.org/stable/c/ceb8459df28d22c225a82d74c0f725f2a935d194