| Message ID | 20190613233159.26687-2-leonardo@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block/cfq : Include check to avoid NULL Pointer | expand |
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2eb87444b157..2c5dd5a295ee 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3210,9 +3210,13 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) static void cfq_choose_cfqg(struct cfq_data *cfqd) { - struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); + struct cfq_group *cfqg; u64 now = ktime_get_ns(); + cfqg = cfq_get_next_cfqg(cfqd); + if (unlikely(!cfqg)) + return; + cfqd->serving_group = cfqg; /* Restore the workload type data */
Checks if cfqg is a valid pointer before dereferencing. There is a explicit chance for cfqg = cfq_get_next_cfqg() to return NULL, so 'cfqg->saved_wl_slice' would be a Null dereferencing. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- block/cfq-iosched.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)