syzbot has found a reproducer for the following crash on: HEAD commit: c25a951c Add linux-next specific files for 20200217 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10df082de00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c727d8fc485ff049 dashboard link: https://syzkaller.appspot.com/bug?extid=adb15cf8c2798e4e0db4 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=112b9d6ee00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=147abb11e00000 Bisection is inconclusive: the bug happens on the oldest tested release. bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14b80c3f200000 final crash: https://syzkaller.appspot.com/x/report.txt?x=16b80c3f200000 console output: https://syzkaller.appspot.com/x/log.txt?x=12b80c3f200000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+adb15cf8c2798e4e0db4@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: use-after-free in __list_add_valid+0x9a/0xa0 lib/list_debug.c:26 Read of size 8 at addr ffff888093bbb1e0 by task syz-executor570/10159 CPU: 1 PID: 10159 Comm: syz-executor570 Not tainted 5.6.0-rc2-next-20200217-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 __list_add_valid+0x9a/0xa0 lib/list_debug.c:26 __list_add include/linux/list.h:67 [inline] list_add_tail include/linux/list.h:100 [inline] cma_listen_on_all drivers/infiniband/core/cma.c:2517 [inline] rdma_listen+0x6b7/0x970 drivers/infiniband/core/cma.c:3628 ucma_listen+0x14d/0x1c0 drivers/infiniband/core/ucma.c:1092 ucma_write+0x2d7/0x3c0 drivers/infiniband/core/ucma.c:1684 __vfs_write+0x8a/0x110 fs/read_write.c:494 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x220/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x446a69 Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fdd8433eda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446a69 RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004 RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c R13: 0000000000000000 R14: 0000000000000000 R15: 20c49ba5e353f7cf Allocated by task 10155: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] __rdma_create_id+0x5e/0x870 drivers/infiniband/core/cma.c:861 ucma_create_id+0x1de/0x620 drivers/infiniband/core/ucma.c:501 ucma_write+0x2d7/0x3c0 drivers/infiniband/core/ucma.c:1684 __vfs_write+0x8a/0x110 fs/read_write.c:494 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x220/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 10157: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x2c0 mm/slab.c:3757 rdma_destroy_id+0x7c6/0xdd0 drivers/infiniband/core/cma.c:1866 ucma_close+0x115/0x310 drivers/infiniband/core/ucma.c:1762 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xbcb/0x3030 kernel/exit.c:802 do_group_exit+0x135/0x360 kernel/exit.c:900 get_signal+0x47c/0x24f0 kernel/signal.c:2734 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:813 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888093bbb000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 480 bytes inside of 2048-byte region [ffff888093bbb000, ffff888093bbb800) The buggy address belongs to the page: page:ffffea00024eeec0 refcount:1 mapcount:0 mapping:00000000f8d67f88 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00026b2908 ffffea00024eee88 ffff8880aa400e00 raw: 0000000000000000 ffff888093bbb000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888093bbb080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093bbb100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888093bbb180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888093bbb200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093bbb280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
