[PATCH] badblocks: avoid checking invalid range in badblocks_check()

[Coly Li]

If prev_badblocks() returns '-1', it means no valid badblocks record
before the checking range. It doesn't make sense to check whether
the input checking range is overlapped with the non-existed invalid
front range.

This patch checkes whether 'prev >= 0' is true before calling
overlap_front(), to void such invalid operations.

Reported-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Coly Li <colyli@xxxxxxx>
---
 block/badblocks.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/badblocks.c b/block/badblocks.c
index fc92d4e18aa3..db4ec8b9b2a8 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -1312,12 +1312,14 @@ static int _badblocks_check(struct badblocks *bb, sector_t s, int sectors,
 	prev = prev_badblocks(bb, &bad, hint);
 
 	/* start after all badblocks */
-	if ((prev + 1) >= bb->count && !overlap_front(bb, prev, &bad)) {
+	if ((prev >= 0) &&
+	    ((prev + 1) >= bb->count) && !overlap_front(bb, prev, &bad)) {
 		len = sectors;
 		goto update_sectors;
 	}
 
-	if (overlap_front(bb, prev, &bad)) {
+	/* Overlapped with front badblocks record */
+	if ((prev >= 0) && overlap_front(bb, prev, &bad)) {
 		if (BB_ACK(p[prev]))
 			acked_badblocks++;
 		else
-- 
2.35.3


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