From 61ebe5a747da649057c37be1c37eb934b4af79ca Mon Sep 17 00:00:00 2001 From: Hailong Liu Date: Thu, 8 Aug 2024 20:19:56 +0800 Subject: mm/vmalloc: fix page mapping if vm_area_alloc_pages() with high order fallback to order 0 The __vmap_pages_range_noflush() assumes its argument pages** contains pages with the same page shift. However, since commit e9c3cda4d86e ("mm, vmalloc: fix high order __GFP_NOFAIL allocations"), if gfp_flags includes __GFP_NOFAIL with high order in vm_area_alloc_pages() and page allocation failed for high order, the pages** may contain two different page shifts (high order and order-0). This could lead __vmap_pages_range_noflush() to perform incorrect mappings, potentially resulting in memory corruption. Users might encounter this as follows (vmap_allow_huge = true, 2M is for PMD_SIZE): kvmalloc(2M, __GFP_NOFAIL|GFP_X) __vmalloc_node_range_noprof(vm_flags=VM_ALLOW_HUGE_VMAP) vm_area_alloc_pages(order=9) ---> order-9 allocation failed and fallback to order-0 vmap_pages_range() vmap_pages_range_noflush() __vmap_pages_range_noflush(page_shift = 21) ----> wrong mapping happens We can remove the fallback code because if a high-order allocation fails, __vmalloc_node_range_noprof() will retry with order-0. Therefore, it is unnecessary to fallback to order-0 here. Therefore, fix this by removing the fallback code. Link: https://lkml.kernel.org/r/20240808122019.3361-1-hailong.liu@oppo.com Fixes: e9c3cda4d86e ("mm, vmalloc: fix high order __GFP_NOFAIL allocations") Signed-off-by: Hailong Liu Reported-by: Tangquan Zheng Reviewed-by: Baoquan He Reviewed-by: Uladzislau Rezki (Sony) Acked-by: Barry Song Acked-by: Michal Hocko Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton --- mm/vmalloc.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6b783baf12a1..af2de36549d6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3584,15 +3584,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid, page = alloc_pages_noprof(alloc_gfp, order); else page = alloc_pages_node_noprof(nid, alloc_gfp, order); - if (unlikely(!page)) { - if (!nofail) - break; - - /* fall back to the zero order allocations */ - alloc_gfp |= __GFP_NOFAIL; - order = 0; - continue; - } + if (unlikely(!page)) + break; /* * Higher order allocations must be able to be treated as -- cgit v1.2.3