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/[email protected]

Fixes: 7f5a08c79df3 ("user_events: Add minimal support for trace_event into ftrace")
Reported-by: Doug Cook <[email protected]>
Signed-off-by: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

0 files changed, 0 insertions, 0 deletions