Medium · published September 4, 2024
In the Linux kernel, the following vulnerability has been resolved:
x86/mm: Fix pti_clone_pgtable() alignment assumption
Guenter reported dodgy crashes on an i386-nosmp build using GCC-11
that had the form of endless traps until entry stack exhaust and then
#DF from the stack guard.
It turned out that pti_clone_pgtable() had alignment assumptions on
the start address, notably it hard assumes start is PMD aligned. This
is true on x86_64, but very much not true on i386.
These assumptions can cause the end condition to malfunction, leading
to a 'short' clone. Guess what happens when the user mapping has a
short copy of the entry text?
Use the correct increment form for addr to avoid alignment
assumptions.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 4.19, < 4.19.320 | 4.19.320 |
| linux/linux_kernel | ≥ 4.20, < 5.4.282 | 5.4.282 |
| linux/linux_kernel | ≥ 5.5, < 5.10.224 | 5.10.224 |
| linux/linux_kernel | ≥ 5.11, < 5.15.165 | 5.15.165 |
| linux/linux_kernel | ≥ 5.16, < 6.1.105 | 6.1.105 |
| linux/linux_kernel | ≥ 6.2, < 6.6.46 | 6.6.46 |
| linux/linux_kernel | ≥ 6.7, < 6.10.5 | 6.10.5 |
| linux/linux_kernel | all versions | — |