From: Song Liu <[email protected]> pti_clone_pmds() assumes that the supplied address is either:
- properly PUD/PMD aligned or - the address is actually mapped which means that independent of the mapping level (PUD/PMD/PTE) the next higher mapping exist. If that's not the case the unaligned address can be incremented by PUD or PMD size wrongly. All callers supply mapped and/or aligned addresses, but for robustness sake, it's better to handle that case proper and to emit a warning. [ tglx: Rewrote changelog and added WARN_ON_ONCE() ] Signed-off-by: Song Liu <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> --- V2: Negate P[UM]D_MASK for checking whether the offset part is 0 --- arch/x86/mm/pti.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, u pud = pud_offset(p4d, addr); if (pud_none(*pud)) { - addr += PUD_SIZE; + WARN_ON_ONCE(addr & ~PUD_MASK); + addr = round_up(addr + 1, PUD_SIZE); continue; } pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) { - addr += PMD_SIZE; + WARN_ON_ONCE(addr & ~PMD_MASK); + addr = round_up(addr + 1, PMD_SIZE); continue; }
