From e269b5d2916d7a696c2d2ed370cea95d95a0675a Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Fri, 29 Nov 2024 16:14:22 -0800 Subject: [PATCH] alloc_tag: fix module allocation tags populated area calculation vm_module_tags_populate() calculation of the populated area assumes that area starts at a page boundary and therefore when new pages are allocation, the end of the area is page-aligned as well. If the start of the area is not page-aligned then allocating a page and incrementing the end of the area by PAGE_SIZE leads to an area at the end but within the area boundary which is not populated. Accessing this are will lead to a kernel panic. Fix the calculation by down-aligning the start of the area and using that as the location allocated pages are mapped to. [gehao@kylinos.cn: fix vm_module_tags_populate's KASAN poisoning logic] Link: https://lkml.kernel.org/r/20241205170528.81000-1-hao.ge@linux.dev [gehao@kylinos.cn: fix panic when CONFIG_KASAN enabled and CONFIG_KASAN_VMALLOC not enabled] Link: https://lkml.kernel.org/r/20241212072126.134572-1-hao.ge@linux.dev Link: https://lkml.kernel.org/r/20241130001423.1114965-1-surenb@google.com Fixes: 0f9b685626da ("alloc_tag: populate memory for module tags as needed") Signed-off-by: Suren Baghdasaryan Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202411132111.6a221562-lkp@intel.com Acked-by: Yu Zhao Tested-by: Adrian Huang Cc: David Wang <00107082@163.com> Cc: Kent Overstreet Cc: Mike Rapoport (Microsoft) Cc: Pasha Tatashin Cc: Sourav Panda Cc: Signed-off-by: Andrew Morton --- lib/alloc_tag.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 3a0413462e9f..7dcebf118a3e 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -408,28 +408,52 @@ static bool find_aligned_area(struct ma_state *mas, unsigned long section_size, static int vm_module_tags_populate(void) { - unsigned long phys_size = vm_module_tags->nr_pages << PAGE_SHIFT; + unsigned long phys_end = ALIGN_DOWN(module_tags.start_addr, PAGE_SIZE) + + (vm_module_tags->nr_pages << PAGE_SHIFT); + unsigned long new_end = module_tags.start_addr + module_tags.size; - if (phys_size < module_tags.size) { + if (phys_end < new_end) { struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages; - unsigned long addr = module_tags.start_addr + phys_size; + unsigned long old_shadow_end = ALIGN(phys_end, MODULE_ALIGN); + unsigned long new_shadow_end = ALIGN(new_end, MODULE_ALIGN); unsigned long more_pages; unsigned long nr; - more_pages = ALIGN(module_tags.size - phys_size, PAGE_SIZE) >> PAGE_SHIFT; + more_pages = ALIGN(new_end - phys_end, PAGE_SIZE) >> PAGE_SHIFT; nr = alloc_pages_bulk_array_node(GFP_KERNEL | __GFP_NOWARN, NUMA_NO_NODE, more_pages, next_page); if (nr < more_pages || - vmap_pages_range(addr, addr + (nr << PAGE_SHIFT), PAGE_KERNEL, + vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL, next_page, PAGE_SHIFT) < 0) { /* Clean up and error out */ for (int i = 0; i < nr; i++) __free_page(next_page[i]); return -ENOMEM; } + vm_module_tags->nr_pages += nr; + + /* + * Kasan allocates 1 byte of shadow for every 8 bytes of data. + * When kasan_alloc_module_shadow allocates shadow memory, + * its unit of allocation is a page. + * Therefore, here we need to align to MODULE_ALIGN. + */ + if (old_shadow_end < new_shadow_end) + kasan_alloc_module_shadow((void *)old_shadow_end, + new_shadow_end - old_shadow_end, + GFP_KERNEL); } + /* + * Mark the pages as accessible, now that they are mapped. + * With hardware tag-based KASAN, marking is skipped for + * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc(). + */ + kasan_unpoison_vmalloc((void *)module_tags.start_addr, + new_end - module_tags.start_addr, + KASAN_VMALLOC_PROT_NORMAL); + return 0; }