Medium · published May 27, 2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: control: Validate buf_len before strnlen() in snd_ctl_elem_init_enum_names()
snd_ctl_elem_init_enum_names() advances pointer p through the names
buffer while decrementing buf_len. If buf_len reaches zero but items
remain, the next iteration calls strnlen(p, 0).
While strnlen(p, 0) returns 0 and would hit the existing name_len == 0
error path, CONFIG_FORTIFY_SOURCE's fortified strnlen() first checks
maxlen against __builtin_dynamic_object_size(). When Clang loses track
of p's object size inside the loop, this triggers a BRK exception panic
before the return value is examined.
Add a buf_len == 0 guard at the loop entry to prevent calling fortified
strnlen() on an exhausted buffer.
Found by kernel fuzz testing through Xiaomi Smartphone.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 3.2, < 5.10.258 | 5.10.258 |
| linux/linux_kernel | ≥ 5.11, < 5.15.209 | 5.15.209 |
| linux/linux_kernel | ≥ 5.16, < 6.1.175 | 6.1.175 |
| linux/linux_kernel | ≥ 6.2, < 6.6.140 | 6.6.140 |
| linux/linux_kernel | ≥ 6.7, < 6.12.86 | 6.12.86 |
| linux/linux_kernel | ≥ 6.13, < 6.18.27 | 6.18.27 |
| linux/linux_kernel | ≥ 6.19, < 7.0.4 | 7.0.4 |