tree 7bb663ac6965bdb99ddacaace92b5f52aebfbe2f
parent 96928d9032a7c34f12a88df879665562bcebf59a
author Beau Belgrave <beaub@linux.microsoft.com> 1682463064 -0700
committer Steven Rostedt (Google) <rostedt@goodmis.org> 1682471026 -0400

tracing/user_events: Ensure write index cannot be negative

The write index indicates which event the data is for and accesses a
per-file array. The index is passed by user processes during write()
calls as the first 4 bytes. Ensure that it cannot be negative by
returning -EINVAL to prevent out of bounds accesses.

Update ftrace self-test to ensure this occurs properly.

Link: https://lkml.kernel.org/r/20230425225107.8525-2-beaub@linux.microsoft.com

Fixes: 7f5a08c79df3 ("user_events: Add minimal support for trace_event into ftrace")
Reported-by: Doug Cook <dcook@linux.microsoft.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>