On 28/11/2020 17:19, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: c84e1efa Merge tag 'asm-generic-fixes-5.10-2' of git://git.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1251d759500000 > kernel config: https://syzkaller.appspot.com/x/.config?x=cb8d1a3819ba4356 > dashboard link: https://syzkaller.appspot.com/bug?extid=12056a09a0311d758e60 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1126cce9500000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1173d2e9500000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+12056a09a0311d758e60@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in radix_tree_next_slot include/linux/radix-tree.h:422 [inline] > BUG: KASAN: use-after-free in idr_for_each+0x206/0x220 lib/idr.c:202 > Read of size 8 at addr ffff888032eb2c40 by task kworker/u4:4/186 > > CPU: 1 PID: 186 Comm: kworker/u4:4 Not tainted 5.10.0-rc5-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: events_unbound io_ring_exit_work > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:118 > print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385 > __kasan_report mm/kasan/report.c:545 [inline] > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562 > radix_tree_next_slot include/linux/radix-tree.h:422 [inline] > idr_for_each+0x206/0x220 lib/idr.c:202 > io_destroy_buffers fs/io_uring.c:8275 [inline] > io_ring_ctx_free fs/io_uring.c:8298 [inline] > io_ring_exit_work+0x3f7/0x7a0 fs/io_uring.c:8375 > process_one_work+0x933/0x15a0 kernel/workqueue.c:2272 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > > Allocated by task 10961: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track mm/kasan/common.c:56 [inline] > __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461 > slab_post_alloc_hook mm/slab.h:526 [inline] > slab_alloc_node mm/slub.c:2891 [inline] > slab_alloc mm/slub.c:2899 [inline] > kmem_cache_alloc+0x122/0x460 mm/slub.c:2904 > radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:274 > idr_get_free+0x4c5/0x940 lib/radix-tree.c:1504 > idr_alloc_u32+0x170/0x2d0 lib/idr.c:46 > idr_alloc+0xc2/0x130 lib/idr.c:87 > io_provide_buffers fs/io_uring.c:4032 [inline] > io_issue_sqe+0x2fc4/0x3d10 fs/io_uring.c:6012 > __io_queue_sqe+0x132/0xda0 fs/io_uring.c:6232 > io_queue_sqe+0x623/0x11f0 fs/io_uring.c:6298 > io_submit_sqe fs/io_uring.c:6367 [inline] > io_submit_sqes+0x15e1/0x28a0 fs/io_uring.c:6596 > __do_sys_io_uring_enter+0xc90/0x1ab0 fs/io_uring.c:8983 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Freed by task 8546: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 > kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 > __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422 > slab_free_hook mm/slub.c:1544 [inline] > slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577 > slab_free mm/slub.c:3142 [inline] > kmem_cache_free+0x82/0x350 mm/slub.c:3158 > rcu_do_batch kernel/rcu/tree.c:2476 [inline] > rcu_core+0x5df/0xe80 kernel/rcu/tree.c:2711 > __do_softirq+0x2a0/0x9f6 kernel/softirq.c:298 > > Last call_rcu(): > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_record_aux_stack+0xc0/0xf0 mm/kasan/generic.c:346 > __call_rcu kernel/rcu/tree.c:2953 [inline] > call_rcu+0xbb/0x700 kernel/rcu/tree.c:3027 > radix_tree_node_free lib/radix-tree.c:308 [inline] > delete_node+0x591/0x8c0 lib/radix-tree.c:571 > __radix_tree_delete+0x190/0x370 lib/radix-tree.c:1377 > radix_tree_delete_item+0xe7/0x230 lib/radix-tree.c:1428 > __io_remove_buffers fs/io_uring.c:3930 [inline] > __io_remove_buffers fs/io_uring.c:3909 [inline] > __io_destroy_buffers+0x161/0x200 fs/io_uring.c:8269 > idr_for_each+0x113/0x220 lib/idr.c:208 > io_destroy_buffers fs/io_uring.c:8275 [inline] > io_ring_ctx_free fs/io_uring.c:8298 [inline] > io_ring_exit_work+0x3f7/0x7a0 fs/io_uring.c:8375 > process_one_work+0x933/0x15a0 kernel/workqueue.c:2272 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > > The buggy address belongs to the object at ffff888032eb2c00 > which belongs to the cache radix_tree_node of size 576 > The buggy address is located 64 bytes inside of > 576-byte region [ffff888032eb2c00, ffff888032eb2e40) > The buggy address belongs to the page: > page:00000000102f3139 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32eb0 > head:00000000102f3139 order:2 compound_mapcount:0 compound_pincount:0 > flags: 0xfff00000010200(slab|head) > raw: 00fff00000010200 dead000000000100 dead000000000122 ffff88801004db40 > raw: 0000000000000000 0000000000170017 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888032eb2b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888032eb2b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >> ffff888032eb2c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff888032eb2c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888032eb2d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > #syz test: git://git.kernel.dk/linux-block dfea9fce29fda6f2f91161677e0e0d9b671bc099 -- Pavel Begunkov
