Hi Steve, On Tue, 2019-03-19 at 23:56 -0400, Steven Rostedt wrote: > Hi Tom, > > I ran the latest kernel (5.1-rc1) with full KASAN enabled, and ran > the > ftrace tests, and hit the following: > > ================================================================== > BUG: KASAN: use-after-free in destroy_hist_field+0x30/0x70 > Read of size 8 at addr ffff888086df2210 by task bash/1694 > > CPU: 6 PID: 1694 Comm: bash Not tainted 5.1.0-rc1-test+ #15 > Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 > v03.03 07/14/2016 > Call Trace: > dump_stack+0x71/0xa0 > ? destroy_hist_field+0x30/0x70 > print_address_description.cold.3+0x9/0x1fb > ? destroy_hist_field+0x30/0x70 > ? destroy_hist_field+0x30/0x70 > kasan_report.cold.4+0x1a/0x33 > ? __kasan_slab_free+0x100/0x150 > ? destroy_hist_field+0x30/0x70 > destroy_hist_field+0x30/0x70 > track_data_destroy+0x55/0xe0 > destroy_hist_data+0x1f0/0x350 > hist_unreg_all+0x203/0x220 > event_trigger_open+0xbb/0x130 > do_dentry_open+0x296/0x700 > ? stacktrace_count_trigger+0x30/0x30 > ? generic_permission+0x56/0x200 > ? __x64_sys_fchdir+0xd0/0xd0 > ? inode_permission+0x55/0x200 > ? security_inode_permission+0x18/0x60 > path_openat+0x633/0x22b0 > ? path_lookupat.isra.50+0x420/0x420 > ? __kasan_kmalloc.constprop.12+0xc1/0xd0 > ? kmem_cache_alloc+0xe5/0x260 > ? getname_flags+0x6c/0x2a0 > ? do_sys_open+0x149/0x2b0 > ? do_syscall_64+0x73/0x1b0 > ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 > ? _raw_write_lock_bh+0xe0/0xe0 > ? __kernel_text_address+0xe/0x30 > ? unwind_get_return_address+0x2f/0x50 > ? __list_add_valid+0x2d/0x70 > ? deactivate_slab.isra.62+0x1f4/0x5a0 > ? getname_flags+0x6c/0x2a0 > ? set_track+0x76/0x120 > do_filp_open+0x11a/0x1a0 > ? may_open_dev+0x50/0x50 > ? _raw_spin_lock+0x7a/0xd0 > ? _raw_write_lock_bh+0xe0/0xe0 > ? __alloc_fd+0x10f/0x200 > do_sys_open+0x1db/0x2b0 > ? filp_open+0x50/0x50 > do_syscall_64+0x73/0x1b0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7fa7b24a4ca2 > Code: 25 00 00 41 00 3d 00 00 41 00 74 4c 48 8d 05 85 7a 0d 00 8b 00 > 85 c0 75 6d 89 f2 b8 01 01 00 00 48 89 fe bf 9c ff ff ff 0f 05 <48> > 3d 00 f0 ff ff 0f 87 a2 00 00 00 48 8b 4c 24 28 64 48 33 0c 25 > RSP: 002b:00007fffbafb3af0 EFLAGS: 00000246 ORIG_RAX: > 0000000000000101 > RAX: ffffffffffffffda RBX: 000055d3648ade30 RCX: 00007fa7b24a4ca2 > RDX: 0000000000000241 RSI: 000055d364a55240 RDI: 00000000ffffff9c > RBP: 00007fffbafb3bf0 R08: 0000000000000020 R09: 0000000000000002 > R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000003 R14: 0000000000000001 R15: 000055d364a55240 > > Allocated by task 1694: > __kasan_kmalloc.constprop.12+0xc1/0xd0 > kmem_cache_alloc_trace+0x11a/0x280 > create_hist_field+0x54/0x460 > create_var_ref+0x2f/0xb0 > event_hist_trigger_func+0x19cb/0x26a0 > event_trigger_write+0x1a7/0x250 > vfs_write+0xe1/0x240 > ksys_write+0xa1/0x130 > do_syscall_64+0x73/0x1b0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Freed by task 1694: > __kasan_slab_free+0x111/0x150 > kfree+0x8d/0x1c0 > destroy_hist_data+0x13b/0x350 > hist_unreg_all+0x203/0x220 > event_trigger_open+0xbb/0x130 > do_dentry_open+0x296/0x700 > path_openat+0x633/0x22b0 > do_filp_open+0x11a/0x1a0 > do_sys_open+0x1db/0x2b0 > do_syscall_64+0x73/0x1b0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > The buggy address belongs to the object at ffff888086df2208 > which belongs to the cache kmalloc-192 of size 192 > The buggy address is located 8 bytes inside of > 192-byte region [ffff888086df2208, ffff888086df22c8) > The buggy address belongs to the page: > page:ffffea00021b7c00 count:1 mapcount:0 mapping:ffff8880d000cc40 > index:0x0 compound_mapcount: 0 > flags: 0xffff000010200(slab|head) > raw: 000ffff000010200 ffffea00021b7708 ffffea000312ee08 > ffff8880d000cc40 > raw: 0000000000000000 00000000001e001e 00000001ffffffff > 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888086df2100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff888086df2180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff888086df2200: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > ffff888086df2280: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc > ffff888086df2300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > Disabling lock debugging due to kernel taint > > I can easily reproduce it with the following commands: > > # cd /sys/kernel/debug/tracing > # echo > 'hist:keys=pid:vals=hitcount:ts0=common_timestamp.usecs:sort=hitcount > :size=2048:clock=global if comm=="ping"' > \ > events/sched/sched_waking/trigger > # echo > 'hist:keys=next_pid:vals=hitcount:wakeup_lat=common_timestamp.usecs- > $ts0:sort=hitcount:size=2048:clock=global:onmax($wakeup_lat).save(nex > t_comm,prev_pid,prev_prio,prev_comm) if next_comm=="ping"' > \ > events/sched/sched_switch/trigger > # echo > '!hist:keys=next_pid:vals=hitcount:wakeup_lat=common_timestamp.usecs- > $ts0:sort=hitcount:size=2048:clock=global:onmax($wakeup_lat).save(nex > t_comm,prev_pid,prev_prio,prev_comm) if next_comm=="ping"' > \ > events/sched/sched_switch/trigger > > And boom, KASAN complains. > > I tried to debug it, but the hist code is rather complex, and I can't > figure out how the var_refs is associated to the fields. I figured > I'd > pass it off to you.
OK, thanks for reporting and trying to debug, will take a look and send a fix.. Tom > > -- Steve
