From: Daniel Axtens <dja@xxxxxxxxxx> Subject: kasan: use apply_to_existing_page_range() for releasing vmalloc shadow kasan_release_vmalloc uses apply_to_page_range to release vmalloc shadow. Unfortunately, apply_to_page_range can allocate memory to fill in page table entries, which is not what we want. Also, kasan_release_vmalloc is called under free_vmap_area_lock, so if apply_to_page_range does allocate memory, we get a sleep in atomic bug: BUG: sleeping function called from invalid context at mm/page_alloc.c:46= 81 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15087, name: Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x199/0x216 lib/dump_stack.c:118 ___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800 __might_sleep+0x95/0x190 kernel/sched/core.c:6753 prepare_alloc_pages mm/page_alloc.c:4681 [inline] __alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730 alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211 alloc_pages include/linux/gfp.h:532 [inline] __get_free_pages+0xc/0x40 mm/page_alloc.c:4786 __pte_alloc_one_kernel include/asm-generic/pgalloc.h:21 [inline] pte_alloc_one_kernel include/asm-generic/pgalloc.h:33 [inline] __pte_alloc_kernel+0x1d/0x200 mm/memory.c:459 apply_to_pte_range mm/memory.c:2031 [inline] apply_to_pmd_range mm/memory.c:2068 [inline] apply_to_pud_range mm/memory.c:2088 [inline] apply_to_p4d_range mm/memory.c:2108 [inline] apply_to_page_range+0x77d/0xa00 mm/memory.c:2133 kasan_release_vmalloc+0xa7/0xc0 mm/kasan/common.c:970 __purge_vmap_area_lazy+0xcbb/0x1f30 mm/vmalloc.c:1313 try_purge_vmap_area_lazy mm/vmalloc.c:1332 [inline] free_vmap_area_noflush+0x2ca/0x390 mm/vmalloc.c:1368 free_unmap_vmap_area mm/vmalloc.c:1381 [inline] remove_vm_area+0x1cc/0x230 mm/vmalloc.c:2209 vm_remove_mappings mm/vmalloc.c:2236 [inline] __vunmap+0x223/0xa20 mm/vmalloc.c:2299 __vfree+0x3f/0xd0 mm/vmalloc.c:2356 __vmalloc_area_node mm/vmalloc.c:2507 [inline] __vmalloc_node_range+0x5d5/0x810 mm/vmalloc.c:2547 __vmalloc_node mm/vmalloc.c:2607 [inline] __vmalloc_node_flags mm/vmalloc.c:2621 [inline] vzalloc+0x6f/0x80 mm/vmalloc.c:2666 alloc_one_pg_vec_page net/packet/af_packet.c:4233 [inline] alloc_pg_vec net/packet/af_packet.c:4258 [inline] packet_set_ring+0xbc0/0x1b50 net/packet/af_packet.c:4342 packet_setsockopt+0xed7/0x2d90 net/packet/af_packet.c:3695 __sys_setsockopt+0x29b/0x4d0 net/socket.c:2117 __do_sys_setsockopt net/socket.c:2133 [inline] __se_sys_setsockopt net/socket.c:2130 [inline] __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2130 do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Switch to using the apply_to_existing_page_range() helper instead, which won't allocate memory. [akpm@xxxxxxxxxxxxxxxxxxxx: s/apply_to_existing_pages/apply_to_existing_page_range/] Link: http://lkml.kernel.org/r/20191205140407.1874-2-dja@xxxxxxxxxx Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shad= ow memory") Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/common.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/mm/kasan/common.c~kasan-use-apply_to_existing_pages-for-releasing-vmalloc-shadow +++ a/mm/kasan/common.c @@ -957,6 +957,7 @@ void kasan_release_vmalloc(unsigned long { void *shadow_start, *shadow_end; unsigned long region_start, region_end; + unsigned long size; region_start = ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); @@ -979,9 +980,11 @@ void kasan_release_vmalloc(unsigned long shadow_end = kasan_mem_to_shadow((void *)region_end); if (shadow_end > shadow_start) { - apply_to_page_range(&init_mm, (unsigned long)shadow_start, - (unsigned long)(shadow_end - shadow_start), - kasan_depopulate_vmalloc_pte, NULL); + size = shadow_end - shadow_start; + apply_to_existing_page_range(&init_mm, + (unsigned long)shadow_start, + size, kasan_depopulate_vmalloc_pte, + NULL); flush_tlb_kernel_range((unsigned long)shadow_start, (unsigned long)shadow_end); } _
