From: Song Liu songliubraving@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 songliubraving@fb.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Ingo Molnar mingo@kernel.org Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908282352470.1938@nanos.tec.linut... Signed-off-by: Sasha Levin sashal@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 c1ba376484a5b..622d5968c9795 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -338,13 +338,15 @@ 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; }