From: Song Liu <songliubrav...@fb.com> [ Upstream commit 825d0b73cd7526b0bb186798583fae810091cbac ]
pti_clone_pmds() assumes that the supplied address is either: - properly PUD/PMD aligned or - the address is actually mapped which means that independently of the mapping level (PUD/PMD/PTE) the next higher mapping exists. If that's not the case the unaligned address can be incremented by PUD or PMD size incorrectly. All callers supply mapped and/or aligned addresses, but for the sake of robustness it's better to handle that case properly and to emit a warning. [ tglx: Rewrote changelog and added WARN_ON_ONCE() ] Signed-off-by: Song Liu <songliubrav...@fb.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Ingo Molnar <mi...@kernel.org> Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/alpine.deb.2.21.1908282352470.1...@nanos.tec.linutronix.de Signed-off-by: Sasha Levin <sas...@kernel.org> --- arch/x86/mm/pti.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index ba22b50f4eca2..7f2140414440d 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, unsigned long end, 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; } -- 2.20.1
