s390/cio: cio_ignore_proc_seq_next should increase position index

if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283 Link: https://lore.kernel.org/r/[email protected] Reviewed-by: Cornelia Huck <[email protected]> Signed-off-by: Christian Borntraeger <[email protected]> Signed-off-by: Vasily Averin <[email protected]> Signed-off-by: Vasily Gorbik <[email protected]>
jbg · Feb 17, 2020 · 8b101a5 · 8b101a5
1 parent 11a48a5
commit 8b101a5
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/drivers/s390/cio/blacklist.c b/drivers/s390/cio/blacklist.c
@@ -303,8 +303,10 @@ static void *
 cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset)
 {
 	struct ccwdev_iter *iter;
+	loff_t p = *offset;
 
-	if (*offset >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1))
+	(*offset)++;
+	if (p >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1))
 		return NULL;
 	iter = it;
 	if (iter->devno == __MAX_SUBCHANNEL) {
@@ -314,7 +316,6 @@ cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset)
 			return NULL;
 	} else
 		iter->devno++;
-	(*offset)++;
 	return iter;
 }