On Tue, Aug 20, 2024 at 04:52:42PM +0800, Hailong Liu wrote:
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 hailong.liu@oppo.com Reported-by: Tangquan Zheng zhengtangquan@oppo.com Reviewed-by: Baoquan He bhe@redhat.com Reviewed-by: Uladzislau Rezki (Sony) urezki@gmail.com Acked-by: Barry Song baohua@kernel.org Acked-by: Michal Hocko mhocko@suse.com Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit 61ebe5a747da649057c37be1c37eb934b4af79ca) Signed-off-by: Hailong Liu hailong.liu@oppo.com
mm/vmalloc.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index c5e30b52844c..a0b650f50faa 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2992,15 +2992,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid, page = alloc_pages(alloc_gfp, order); else page = alloc_pages_node(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 -- 2.25.1
Now queued up, thanks.
greg k-h