• Daniel Axtens's avatar
    kasan: use apply_to_existing_page_range() for releasing vmalloc shadow · e218f1ca
    Daniel Axtens authored
    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:4681
    	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@linux-foundation.org: s/apply_to_existing_pages/apply_to_existing_page_range/]
    Link: http://lkml.kernel.org/r/20191205140407.1874-2-dja@axtens.net
    Fixes: 3c5c3cfb
    
     ("kasan: support backing vmalloc space with real shadow memory")
    Signed-off-by: default avatarDaniel Axtens <dja@axtens.net>
    Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
    Reviewed-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
    Cc: Alexander Potapenko <glider@google.com>
    Cc: Qian Cai <cai@lca.pw>
    Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e218f1ca