On Thu, 13 Jul 2023 22:23:20 +0800
Zheng Yejian [off-list ref] wrote:

On 2023/7/13 22:14, Zheng Yejian wrote:

quoted

kmemleak reports:
   unreferenced object 0xffff88814d14e200 (size 256):
     comm "cat", pid 336, jiffies 4294871818 (age 779.490s)
     hex dump (first 32 bytes):
       04 00 01 03 00 00 00 00 08 00 00 00 00 00 00 00  ................
       0c d8 c8 9b ff ff ff ff 04 5a ca 9b ff ff ff ff  .........Z......
     backtrace:
       [<ffffffff9bdff18f>] __kmalloc+0x4f/0x140
       [<ffffffff9bc9238b>] trace_find_next_entry+0xbb/0x1d0
       [<ffffffff9bc9caef>] trace_print_lat_context+0xaf/0x4e0
       [<ffffffff9bc94490>] print_trace_line+0x3e0/0x950
       [<ffffffff9bc95499>] tracing_read_pipe+0x2d9/0x5a0
       [<ffffffff9bf03a43>] vfs_read+0x143/0x520
       [<ffffffff9bf04c2d>] ksys_read+0xbd/0x160
       [<ffffffff9d0f0edf>] do_syscall_64+0x3f/0x90
       [<ffffffff9d2000aa>] entry_SYSCALL_64_after_hwframe+0x6e/0xd8

when reading file 'trace_pipe', 'iter->temp' is allocated or relocated
in trace_find_next_entry() but not freed before 'trace_pipe' is closed.

To fix it, free 'iter->temp' in tracing_release_pipe().
  

Sorry, forget the Fixes tag:(

Is following Fixes right?
Fixes: ff895103a84a ("tracing: Save off entry when peeking at next entry")

That's the one I already added ;-)

Don't worry too much about adding fixes, I will always analyze a fix patch
to find out what it actually fixes. If you add one, I'll still confirm it.

-- Steve

quoted

Signed-off-by: Zheng Yejian <redacted>
---
  kernel/trace/trace.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4529e264cb86..94cfaa884578 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c

@@ -6764,6 +6764,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
  
  	free_cpumask_var(iter->started);
  	kfree(iter->fmt);
+	kfree(iter->temp);
  	mutex_destroy(&iter->mutex);
  	kfree(iter);