CVE-2023-53679 in Linux
Summary
by MITRE • 10/07/2025
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 ]---
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
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Analysis
by VulDB Data Team • 03/01/2026
The vulnerability identified as CVE-2023-53679 resides within the Linux kernel's mt7601u wireless driver, specifically targeting an integer underflow condition that can lead to a null pointer dereference. This flaw manifests in the function mt7601u_rx_skb_from_seg() where an improperly validated dma_len variable from URB packets can trigger an integer underflow in seg_len within mt7601u_rx_process_seg(). The underflow causes the bad_frame checks to be bypassed, ultimately resulting in a dereference of a null pointer p, which leads to a kernel panic or potential privilege escalation.
The technical root cause of this vulnerability aligns with CWE-191, which describes integer underflow conditions, and can be mapped to ATT&CK technique T1068, which involves exploiting local privilege escalation vulnerabilities. The flaw occurs during packet processing when the driver fails to validate that dma_len exceeds a minimum segment length, allowing maliciously crafted packets to manipulate the integer arithmetic. The KASAN report indicates the null pointer dereference occurs in skb_add_rx_frag(), a core kernel function responsible for adding received fragments to socket buffers, which demonstrates the severity of the impact on kernel memory management.
This vulnerability presents a significant operational risk to systems utilizing the mt7601u wireless USB adapter, as it can be exploited through specially crafted wireless packets to cause system crashes or potentially enable privilege escalation. The exploitation requires an attacker to be within range of the affected wireless network or to have access to a device with the vulnerable driver loaded. The fix implemented involves adding a validation check to ensure that dma_len is greater than min_seg_len, preventing the integer underflow condition from occurring and thereby eliminating the path to the null pointer dereference.
The discovery of this vulnerability through a modified version of syzkaller highlights the effectiveness of automated fuzzing tools in identifying kernel-level security issues. The mt7601u driver, which supports MediaTek MT7601U chipsets, is commonly found in various wireless USB adapters, making this vulnerability widespread across different hardware platforms. The mitigation strategy involves applying the kernel patch that enforces proper validation of dma_len values, ensuring that the integer underflow condition cannot be triggered by malformed input packets. Organizations should prioritize updating their kernel versions to include this fix, particularly in environments where wireless network access is available to untrusted users or where the wireless adapter is exposed to potential malicious packet injection attacks.