From: Joerg Roedel <jroedel@xxxxxxx> On x86-32 with PTI enabled, parts of the kernel page-tables are not shared between processes. This can cause mappings in the vmalloc/ioremap area to persist in some page-tables after the regions is unmapped and released. When the region is re-used the processes with the old mappings do not fault in the new mappings but still access the old ones. This causes undefined behavior, in reality often data corruption, kernel oopses and panics and even spontaneous reboots. Fix this problem by activly syncing unmaps in the vmalloc/ioremap area to all page-tables in the system. References: https://bugzilla.suse.com/show_bug.cgi?id=1118689 Fixes: 7757d607c6b3 ('x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32') Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> --- mm/vmalloc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 4fa8d84599b0..322b11a374fd 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -132,6 +132,8 @@ static void vunmap_page_range(unsigned long addr, unsigned long end) continue; vunmap_p4d_range(pgd, addr, next); } while (pgd++, addr = next, addr != end); + + vmalloc_sync_all(); } static int vmap_pte_range(pmd_t *pmd, unsigned long addr, -- 2.17.1
