TLDRVuln - Cybersecurity Vulnerabilities Made Simple

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

wifi: mt7601u: fix an integer underflow

Fix an integer underflow that leads to a null pointer dereference in

'mt7601u_rx_skb_from_seg()'. The variable 'dma_len' in the URB packet

could be manipulated, which could trigger an integer underflow of

'seg_len' in 'mt7601u_rx_process_seg()'. This underflow subsequently

causes the 'bad_frame' checks in 'mt7601u_rx_skb_from_seg()' to be

bypassed, eventually leading to a dereference of the pointer 'p', which

is a null pointer.

Ensure that 'dma_len' is greater than 'min_seg_len'.

Found by a modified version of syzkaller.

KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]

CPU: 0 PID: 12 Comm: ksoftirqd/0 Tainted: G W O 5.14.0+

#139

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS

rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014

RIP: 0010:skb_add_rx_frag+0x143/0x370

Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44

89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02

00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00

RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202

RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000

RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8

RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010

R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000

R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008

FS: 0000000000000000(0000) GS:ffff88811a800000(0000)

knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

PKRU: 55555554

Call Trace:

mt7601u_rx_tasklet+0xc73/0x1270

? mt7601u_submit_rx_buf.isra.0+0x510/0x510

? tasklet_action_common.isra.0+0x79/0x2f0

tasklet_action_common.isra.0+0x206/0x2f0

__do_softirq+0x1b5/0x880

? tasklet_unlock+0x30/0x30

run_ksoftirqd+0x26/0x50

smpboot_thread_fn+0x34f/0x7d0

? smpboot_register_percpu_thread+0x370/0x370

kthread+0x3a1/0x480

? set_kthread_struct+0x120/0x120

ret_from_fork+0x1f/0x30

Modules linked in: 88XXau(O) 88x2bu(O)

---[ end trace 57f34f93b4da0f9b ]---