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Subject[PATCH] tracing: Avoid memory leak in process_system_preds()
Date
When failing in the allocation of filter_item, process_system_preds()
goes to fail_mem, where the allocated filter is freed.

However, this leads to memory leak of filter->filter_string and
filter->prog, which is allocated before and in process_preds().
This bug has been detected by kmemleak as well.

Fix this by changing kfree to __free_fiter.

unreferenced object 0xffff8880658007c0 (size 32):
comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
hex dump (first 32 bytes):
63 6f 6d 6d 6f 6e 5f 70 69 64 20 20 3e 20 31 30 common_pid > 10
00 00 00 00 00 00 00 00 65 73 00 00 00 00 00 00 ........es......
backtrace:
[<0000000067441602>] kstrdup+0x2d/0x60
[<00000000141cf7b7>] apply_subsystem_event_filter+0x378/0x932
[<000000009ca32334>] subsystem_filter_write+0x5a/0x90
[<0000000072da2bee>] vfs_write+0xe1/0x240
[<000000004f14f473>] ksys_write+0xb4/0x150
[<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
[<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff888060c22d00 (size 64):
comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 e8 d7 41 80 88 ff ff ...........A....
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000b8c1b109>] process_preds+0x243/0x1820
[<000000003972c7f0>] apply_subsystem_event_filter+0x3be/0x932
[<000000009ca32334>] subsystem_filter_write+0x5a/0x90
[<0000000072da2bee>] vfs_write+0xe1/0x240
[<000000004f14f473>] ksys_write+0xb4/0x150
[<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
[<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff888041d7e800 (size 512):
comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
hex dump (first 32 bytes):
70 bc 85 97 ff ff ff ff 0a 00 00 00 00 00 00 00 p...............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<000000001e04af34>] process_preds+0x71a/0x1820
[<000000003972c7f0>] apply_subsystem_event_filter+0x3be/0x932
[<000000009ca32334>] subsystem_filter_write+0x5a/0x90
[<0000000072da2bee>] vfs_write+0xe1/0x240
[<000000004f14f473>] ksys_write+0xb4/0x150
[<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
[<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Keita Suzuki <keitasuzuki.park@sslab.ics.keio.ac.jp>
---
kernel/trace/trace_events_filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index c9a74f82b14a..bf44f6bbd0c3 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1662,7 +1662,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,
parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
return -EINVAL;
fail_mem:
- kfree(filter);
+ __free_filter(filter);
/* If any call succeeded, we still need to sync */
if (!fail)
tracepoint_synchronize_unregister();
--
2.17.1
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