This is a note to let you know that I've just added the patch titled
tracing/user_events: Ensure write index cannot be negative
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-user_events-ensure-write-index-cannot-be-neg.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9c3a74bd3208566652109977459a54699d909421
Author: Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>
Date: Tue Apr 25 15:51:04 2023 -0700
tracing/user_events: Ensure write index cannot be negative
[ Upstream commit cd98c93286a30cc4588dfd02453bec63c2f4acf4 ]
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@xxxxxxxxxxxxxxxxxxx
Fixes: 7f5a08c79df3 ("user_events: Add minimal support for trace_event into ftrace")
Reported-by: Doug Cook <dcook@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 908e8a13c675b..625cab4b9d945 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -1398,6 +1398,9 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
if (unlikely(copy_from_iter(&idx, sizeof(idx), i) != sizeof(idx)))
return -EFAULT;
+ if (idx < 0)
+ return -EINVAL;
+
rcu_read_lock_sched();
refs = rcu_dereference_sched(info->refs);
diff --git a/tools/testing/selftests/user_events/ftrace_test.c b/tools/testing/selftests/user_events/ftrace_test.c
index 404a2713dcae8..1bc26e6476fc3 100644
--- a/tools/testing/selftests/user_events/ftrace_test.c
+++ b/tools/testing/selftests/user_events/ftrace_test.c
@@ -294,6 +294,11 @@ TEST_F(user, write_events) {
ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 3));
after = trace_bytes();
ASSERT_GT(after, before);
+
+ /* Negative index should fail with EINVAL */
+ reg.write_index = -1;
+ ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
+ ASSERT_EQ(EINVAL, errno);
}
TEST_F(user, write_fault) {
