[Devel] [PATCH rh7] fs/fuse kio: add a sanity check on statistic inc

[Konstantin Khorenko]

As there are still possible cases when we expect code to work without
statistic inited, it's theoretically possible some day we again get an
update request for non-inited stat struct, and corrupt stack-protector
cookie and who knows what alse.

So add a sanity check to prevent it.

https://jira.sw.ru/browse/PSBM-96128

Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 fs/fuse/kio/pcs/fuse_stat.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/fuse/kio/pcs/fuse_stat.c b/fs/fuse/kio/pcs/fuse_stat.c
index b57be607f5e1..c91bfe8b3bf7 100644
--- a/fs/fuse/kio/pcs/fuse_stat.c
+++ b/fs/fuse/kio/pcs/fuse_stat.c
@@ -31,6 +31,12 @@ static u64 lat_oreder_list[] = {
 
 static inline void fuse_val_stat_update(struct fuse_val_stat *s, u64 val)
 {
+	/*
+	 * Sanity check. In case s == NULL, stack protector cookie is
+	 * corrupted, quite difficult to debug.
+	 */
+	BUG_ON(!s);
+
 	preempt_disable();
 	if (!__this_cpu_read(s->events)) {
 		__this_cpu_write(s->val_min, val);
@@ -48,6 +54,11 @@ void fuse_latency_update(struct fuse_lat_stat *s, u64 val)
 {
 	int i;
 
+	/*
+	 * Sanity check. In case s == NULL, stack protector cookie is
+	 * corrupted, quite difficult to debug.
+	 */
+	BUG_ON(!s);
 	this_cpu_inc(s->count);
 	for (i = LAT_ORDER1; i <= LAT_ORDER5; i++) {
 		if (likely(val <= lat_oreder_list[i])) {
-- 
2.15.1