From: Beau Belgrave Date: Tue, 25 Apr 2023 22:51:04 +0000 (-0700) Subject: tracing/user_events: Ensure write index cannot be negative X-Git-Tag: v6.6.17~4909^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cd98c93286a30cc4588dfd02453bec63c2f4acf4;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index eadb58a..546d47a 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -1824,6 +1824,9 @@ 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 aceafac..91272f9 100644 --- a/tools/testing/selftests/user_events/ftrace_test.c +++ b/tools/testing/selftests/user_events/ftrace_test.c @@ -296,6 +296,11 @@ 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) {