Bug 9269 - tracing: Add NULL checks for buffer in ring_buffer_free_read_page()
Summary: tracing: Add NULL checks for buffer in ring_buffer_free_read_page()
Status: RESOLVED FIXED
Alias: None
Product: ANCK 5.10 Dev
Classification: ANCK
Component: ARCH(unspecified) (show other bugs) ARCH(unspecified)
Version: unspecified
Hardware: All Linux
: P3-Medium S3-normal
Target Milestone: ---
Assignee: went123
QA Contact: shuming
URL:
Whiteboard:
Keywords: Bugfix
Depends on:
Blocks:
 
Reported: 2024-06-03 14:12 UTC by went123
Modified: 2024-06-06 17:25 UTC (History)
2 users (show)

See Also:

Attachments
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description went123 2024-06-03 14:12:46 UTC 
In a previous commit 7433632c9ff6, buffer, buffer->buffers and
buffer->buffers[cpu] in ring_buffer_wake_waiters() can be NULL,
and thus the related checks are added.

However, in the same call stack, these variables are also used in
ring_buffer_free_read_page():

tracing_buffers_release()
  ring_buffer_wake_waiters(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> Add checks by previous commit
  ring_buffer_free_read_page(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> No check

Thus, to avod possible null-pointer derefernces, the related checks
should be added.

These results are reported by a static tool designed by myself.

Link: https://lkml.kernel.org/r/20230113125501.760324-1-baijiaju1990@gmail.com