oprofile: fix uninitialized use of struct op_entry

Impact: fix crash

In case of losing samples struct op_entry could have been used
uninitialized causing e.g. a wrong preemption count or NULL pointer
access. This patch fixes this.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 2e03b6d796d3..e76d715e4342 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -393,16 +393,21 @@ oprofile_write_reserve(struct op_entry *entry, struct pt_regs * const regs,
         return;
 
 fail:
+        entry->event = NULL;
         cpu_buf->sample_lost_overflow++;
 }
 
 int oprofile_add_data(struct op_entry *entry, unsigned long val)
 {
+        if (!entry->event)
+                return 0;
         return op_cpu_buffer_add_data(entry, val);
 }
 
 int oprofile_write_commit(struct op_entry *entry)
 {
+        if (!entry->event)
+                return -EINVAL;
         return op_cpu_buffer_write_commit(entry);
 }