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 commite9c3cda4d8
("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:e9c3cda4d8
("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>
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mm/vmalloc.c
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mm/vmalloc.c
@ -3584,15 +3584,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
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page = alloc_pages_noprof(alloc_gfp, order);
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page = alloc_pages_noprof(alloc_gfp, order);
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else
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else
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page = alloc_pages_node_noprof(nid, alloc_gfp, order);
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page = alloc_pages_node_noprof(nid, alloc_gfp, order);
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if (unlikely(!page)) {
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if (unlikely(!page))
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if (!nofail)
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break;
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break;
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/* fall back to the zero order allocations */
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alloc_gfp |= __GFP_NOFAIL;
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order = 0;
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continue;
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}
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/*
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/*
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* Higher order allocations must be able to be treated as
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* Higher order allocations must be able to be treated as
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