CVE-2026-80580fbdev: bound mode sysfs output to the sysfs buffer

Official description

In the Linux kernel, the following vulnerability has been resolved: fbdev: bound mode sysfs output to the sysfs buffer mode_string() uses snprintf() which can return a value larger than the remaining buffer space. show_modes() accumulates the return value into i without checking whether i has reached PAGE_SIZE, causing the offset to advance past the sysfs buffer if the modelist is long enough. Add a size parameter to mode_string() and use scnprintf() to return only the bytes actually written. Add an early return when offset already exceeds the buffer. In show_modes(), stop accumulating once the buffer is full.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/873a1aa15c313263f2e18b38cf525623cc4fabf6
• https://git.kernel.org/stable/c/d15d51fb26e830af58f3f21964f1c09c239077ea