CVE-2025-38153

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

net: usb: aqc111: fix error handling of usbnet read calls

Syzkaller, courtesy of syzbot, identified an error (see report [1]) in aqc111 driver, caused by incomplete sanitation of usb read calls results. This problem is quite similar to the one fixed in commit 920a9fa27e78 (net: asix: add proper error handling of usb read errors).

For instance, usbnet_read_cmd() may read fewer than size bytes, even if the caller expected the full amount, and aqc111_read_cmd() will not check its result properly. As [1] shows, this may lead to MAC address in aqc111_bind() being only partly initialized, triggering KMSAN warnings.

Fix the issue by verifying that the number of bytes read is as expected and not less.

[1] Partial syzbot report: BUG: KMSAN: uninit-value in is_valid_ether_addr include/linux/etherdevice.h:208 [inline] BUG: KMSAN: uninit-value in usbnet_probe+0x2e57/0x4390 drivers/net/usb/usbnet.c:1830 is_valid_ether_addr include/linux/etherdevice.h:208 [inline] usbnet_probe+0x2e57/0x4390 drivers/net/usb/usbnet.c:1830 usb_probe_interface+0xd01/0x1310 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x4d1/0xd90 drivers/base/dd.c:658 __driver_probe_device+0x268/0x380 drivers/base/dd.c:800 …

Uninit was stored to memory at: dev_addr_mod+0xb0/0x550 net/core/dev_addr_lists.c:582 __dev_addr_set include/linux/netdevice.h:4874 [inline] eth_hw_addr_set include/linux/etherdevice.h:325 [inline] aqc111_bind+0x35f/0x1150 drivers/net/usb/aqc111.c:717 usbnet_probe+0xbe6/0x4390 drivers/net/usb/usbnet.c:1772 usb_probe_interface+0xd01/0x1310 drivers/usb/core/driver.c:396 …

Uninit was stored to memory at: ether_addr_copy include/linux/etherdevice.h:305 [inline] aqc111_read_perm_mac drivers/net/usb/aqc111.c:663 [inline] aqc111_bind+0x794/0x1150 drivers/net/usb/aqc111.c:713 usbnet_probe+0xbe6/0x4390 drivers/net/usb/usbnet.c:1772 usb_probe_interface+0xd01/0x1310 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:-1 [inline] …

Local variable buf.i created at: aqc111_read_perm_mac drivers/net/usb/aqc111.c:656 [inline] aqc111_bind+0x221/0x1150 drivers/net/usb/aqc111.c:713 usbnet_probe+0xbe6/0x4390 drivers/net/usb/usbnet.c:1772

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/11273279012c922f37cfb4dd95d142803fc07b98
• https://git.kernel.org/stable/c/30a9e834c74e260533b8d0885e3c89f6f32f7993
• https://git.kernel.org/stable/c/405b0d610745fb5e84fc2961d9b960abb9f3d107
• https://git.kernel.org/stable/c/60790d287c1a1ced3554d4a87c2f27bf299a932a
• https://git.kernel.org/stable/c/7c01863b1c47f040d9674171e77789a423b9b128
• https://git.kernel.org/stable/c/8c97655275482ef5384ce0501640630a0fc0f6f4
• https://git.kernel.org/stable/c/acb47a40b5e38be03ef659b7bacdddc592ed73b7
• https://git.kernel.org/stable/c/f398d2dfe450ce2c031d10b585448862d74a0501
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html