[PATCH] e2fsck: skip sorting extents if there are no valid extents

From: Harshad Shirwadkar <redacted>

At the end of a fast commit replay, e2fsck tries merging extents in a
inode. This patch fixes a bug in this logic where we were continuing
this action even if there were no extents to merge resulting in
accessing illegal memory.

Signed-off-by: Harshad Shirwadkar <redacted>
---
 e2fsck/journal.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/e2fsck/journal.c b/e2fsck/journal.c
index fe4e018d..2e867234 100644
--- a/e2fsck/journal.c
+++ b/e2fsck/journal.c

@@ -464,6 +464,9 @@ static void ex_sort_and_merge(struct extent_list *list)
 		}
 	}
 
+	if (list->count == 0)
+		return;
+
 	/* Now sort by logical offset */
 	qsort(list->extents, list->count, sizeof(list->extents[0]),
 		ex_compar);

-- 
2.34.0.rc1.387.gb447b232ab-goog

On Wed, 17 Nov 2021 08:50:15 -0800, Harshad Shirwadkar wrote:

From: Harshad Shirwadkar <redacted>

At the end of a fast commit replay, e2fsck tries merging extents in a
inode. This patch fixes a bug in this logic where we were continuing
this action even if there were no extents to merge resulting in
accessing illegal memory.

[...]

Applied, thanks!

[1/1] e2fsck: skip sorting extents if there are no valid extents
      commit: 54183fea07676d185b2c169c45a7c1adc7e3e26e

Best regards,
-- 
Theodore Ts'o [off-list ref]