(cc Yury and KASAN developers) On Tue, 06 Sep 2022 06:21:39 -0700 syzbot <syzbot+08ca1fa706a22cc17efe@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 840126e36e8f Add linux-next specific files for 20220906 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1216969b080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=239c4c4e44185526 > dashboard link: https://syzkaller.appspot.com/bug?extid=08ca1fa706a22cc17efe > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/1b9017e387a8/disk-840126e3.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/12182558f88d/vmlinux-840126e3.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+08ca1fa706a22cc17efe@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: slab-out-of-bounds in _find_next_bit+0x143/0x160 lib/find_bit.c:109 Presumably the for_each_clear_bitrange() in pcpu_balance_populated(). > Read of size 8 at addr ffff8880175766b8 by task kworker/1:1/26 An eight byte read... > CPU: 1 PID: 26 Comm: kworker/1:1 Not tainted 6.0.0-rc4-next-20220906-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 > Workqueue: events pcpu_balance_workfn > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:287 [inline] > print_report+0x164/0x463 mm/kasan/report.c:398 > kasan_report+0xbb/0x1f0 mm/kasan/report.c:486 > _find_next_bit+0x143/0x160 lib/find_bit.c:109 > find_next_bit include/linux/find.h:55 [inline] > pcpu_balance_populated mm/percpu.c:2086 [inline] > pcpu_balance_workfn+0x6c0/0xea0 mm/percpu.c:2246 > process_one_work+0x991/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e4/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > </TASK> > > Allocated by task 26: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45 > kasan_set_track+0x21/0x30 mm/kasan/common.c:52 > ____kasan_kmalloc mm/kasan/common.c:371 [inline] > ____kasan_kmalloc mm/kasan/common.c:330 [inline] > __kasan_kmalloc+0xa1/0xb0 mm/kasan/common.c:380 > kasan_kmalloc include/linux/kasan.h:211 [inline] > __do_kmalloc_node mm/slab_common.c:931 [inline] > __kmalloc+0x54/0xc0 mm/slab_common.c:944 > kmalloc include/linux/slab.h:565 [inline] > kzalloc include/linux/slab.h:696 [inline] > pcpu_mem_zalloc+0x70/0xa0 mm/percpu.c:514 > pcpu_alloc_chunk mm/percpu.c:1446 [inline] > pcpu_create_chunk+0x23/0x930 mm/percpu-vm.c:338 > pcpu_balance_populated mm/percpu.c:2108 [inline] > pcpu_balance_workfn+0xc4e/0xea0 mm/percpu.c:2246 > process_one_work+0x991/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e4/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > The buggy address belongs to the object at ffff888017576600 > which belongs to the cache kmalloc-192 of size 192 > The buggy address is located 184 bytes inside of > 192-byte region [ffff888017576600, ffff8880175766c0) At offset 184 of a 192-byte region. So what's wrong with doing that? Does KASAN have an off-by-one? > The buggy address belongs to the physical page: > page:ffffea00005d5d80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x17576 > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > raw: 00fff00000000200 ffff888011841a00 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 2455007664, free_ts 0 > prep_new_page mm/page_alloc.c:2544 [inline] > get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4294 > __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5552 > alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2113 > alloc_pages+0x22f/0x270 mm/mempolicy.c:2275 > alloc_slab_page mm/slub.c:1734 [inline] > allocate_slab+0x213/0x300 mm/slub.c:1879 > new_slab mm/slub.c:1932 [inline] > ___slab_alloc+0xad0/0x1440 mm/slub.c:3113 > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3211 > slab_alloc_node mm/slub.c:3296 [inline] > __kmem_cache_alloc_node+0x18a/0x3d0 mm/slub.c:3369 > __do_kmalloc_node mm/slab_common.c:930 [inline] > __kmalloc_node_track_caller+0x45/0xc0 mm/slab_common.c:951 > __do_krealloc mm/slab_common.c:1324 [inline] > krealloc+0x8c/0xf0 mm/slab_common.c:1357 > add_sysfs_param+0xca/0x960 kernel/params.c:651 > kernel_add_sysfs_param kernel/params.c:812 [inline] > param_sysfs_builtin kernel/params.c:851 [inline] > param_sysfs_init+0x301/0x43b kernel/params.c:970 > do_one_initcall+0xfe/0x650 init/main.c:1307 > do_initcall_level init/main.c:1382 [inline] > do_initcalls init/main.c:1398 [inline] > do_basic_setup init/main.c:1417 [inline] > kernel_init_freeable+0x6ff/0x788 init/main.c:1637 > kernel_init+0x1a/0x1d0 init/main.c:1525 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > page_owner free stack trace missing > > Memory state around the buggy address: > ffff888017576580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff888017576600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff888017576680: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc > ^ > ffff888017576700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff888017576780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
