wifi: mt76: mt7921s: fix slab-out-of-bounds access in sdio host

Summary

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7921s: fix slab-out-of-bounds access in sdio host SDIO may need addtional 511 bytes to align bus operation. If the tailroom of this skb is not big enough, we would access invalid memory region. For low level operation, increase skb size to keep valid memory access in SDIO host. Error message: [69.951] BUG: KASAN: slab-out-of-bounds in sg_copy_buffer+0xe9/0x1a0 [69.951] Read of size 64 at addr ffff88811c9cf000 by task kworker/u16:7/451 [69.951] CPU: 4 PID: 451 Comm: kworker/u16:7 Tainted: G W OE 6.1.0-rc5 #1 [69.951] Workqueue: kvub300c vub300_cmndwork_thread [vub300] [69.951] Call Trace: [69.951] <TASK> [69.952] dump_stack_lvl+0x49/0x63 [69.952] print_report+0x171/0x4a8 [69.952] kasan_report+0xb4/0x130 [69.952] kasan_check_range+0x149/0x1e0 [69.952] memcpy+0x24/0x70 [69.952] sg_copy_buffer+0xe9/0x1a0 [69.952] sg_copy_to_buffer+0x12/0x20 [69.952] __command_write_data.isra.0+0x23c/0xbf0 [vub300] [69.952] vub300_cmndwork_thread+0x17f3/0x58b0 [vub300] [69.952] process_one_work+0x7ee/0x1320 [69.952] worker_thread+0x53c/0x1240 [69.952] kthread+0x2b8/0x370 [69.952] ret_from_fork+0x1f/0x30 [69.952] </TASK> [69.952] Allocated by task 854: [69.952] kasan_save_stack+0x26/0x50 [69.952] kasan_set_track+0x25/0x30 [69.952] kasan_save_alloc_info+0x1b/0x30 [69.952] __kasan_kmalloc+0x87/0xa0 [69.952] __kmalloc_node_track_caller+0x63/0x150 [69.952] kmalloc_reserve+0x31/0xd0 [69.952] __alloc_skb+0xfc/0x2b0 [69.952] __mt76_mcu_msg_alloc+0xbf/0x230 [mt76] [69.952] mt76_mcu_send_and_get_msg+0xab/0x110 [mt76] [69.952] __mt76_mcu_send_firmware.cold+0x94/0x15d [mt76] [69.952] mt76_connac_mcu_send_ram_firmware+0x415/0x54d [mt76_connac_lib] [69.952] mt76_connac2_load_ram.cold+0x118/0x4bc [mt76_connac_lib] [69.952] mt7921_run_firmware.cold+0x2e9/0x405 [mt7921_common] [69.952] mt7921s_mcu_init+0x45/0x80 [mt7921s] [69.953] mt7921_init_work+0xe1/0x2a0 [mt7921_common] [69.953] process_one_work+0x7ee/0x1320 [69.953] worker_thread+0x53c/0x1240 [69.953] kthread+0x2b8/0x370 [69.953] ret_from_fork+0x1f/0x30 [69.953] The buggy address belongs to the object at ffff88811c9ce800 which belongs to the cache kmalloc-2k of size 2048 [69.953] The buggy address is located 0 bytes to the right of 2048-byte region [ffff88811c9ce800, ffff88811c9cf000) [69.953] Memory state around the buggy address: [69.953] ffff88811c9cef00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [69.953] ffff88811c9cef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [69.953] >ffff88811c9cf000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [69.953] ^ [69.953] ffff88811c9cf080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [69.953] ffff88811c9cf100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Timeline

1. Dec 24, 2025, 10:55 AM UTCCVE published295 days
2. Oct 15, 2026, 9:32 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 15, 2026, 9:41 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 764dee47e2c1ed828c8a51cbf58f89b5e3ded11b · fixed in 8b5174a7f25d03df0ffa171ff86de383a89e8e89; From 764dee47e2c1ed828c8a51cbf58f89b5e3ded11b · fixed in 0b358e36433d2c46a65488a146bf8b4623fc5bbb; From 764dee47e2c1ed828c8a51cbf58f89b5e3ded11b · fixed in aec4cf2ea0797e28f18f8dbe01943a56d987fe56

• Linux Linux

  5.16

• KernelLinux

  From 5.16.0 · fixed in 6.1.16; From 6.2.0 · fixed in 6.2.3

References 3