From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
The destroy_actions() function will call track_data_destroy() which calls
destroy_hist_field() on the data->track_data.var_ref. This checks the
hist_field flags for HIST_FIELD_FL_VAR_REF, and if it is set it will not
free the variable as it will be freed later.
destroy_hist_fields() frees the hist_fields that are marked with
HIST_FIELD_VAR_REF.
The issue is that destroy_hist_fields() is called before destroy_actions()
and frees the data->track_data.var_ref before destroy_actions() is called.
When the destroy_hist_field() checks the hist_field's flag for
HIST_FIELD_FL_VAR_REF, the hist_field has already been freed, and KASAN
reports a "used after free" warning:
==================================================================
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
By calling destroy_actions() before destroy_hist_fields() will move the
check before the free.
Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
kernel/trace/trace_events_hist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index ca46339f3009..c510a0e89623 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4992,10 +4992,10 @@ static void destroy_hist_data(struct hist_trigger_data
*hist_data)
return;
destroy_hist_trigger_attrs(hist_data->attrs);
+ destroy_actions(hist_data);
destroy_hist_fields(hist_data);
tracing_map_destroy(hist_data->map);
- destroy_actions(hist_data);
destroy_field_vars(hist_data);
destroy_field_var_hists(hist_data);
--
2.20.1
