Re: [PATCH] Revert "null_blk: allow byte aligned memory offsets"

[Keith Busch <kbusch@kernel.org>]

On Tue, Nov 11, 2025 at 02:08:33PM -0800, Bart Van Assche wrote:
> This reverts commit 3451cf34f51bb70c24413abb20b423e64486161b and fixes
> the following KASAN complaint when running test zbd/013

Can I please just get one chance to fix it before a kneejerk revert??

This was in v1, it was mistakenly dropped from v2.

---
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index f1e67962ecaeb..55c3f4d62c2e3 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1240,9 +1240,12 @@ static blk_status_t null_transfer(struct nullb *nullb, struct page *page,

        p = kmap_local_page(page) + off;
        if (!is_write) {
-               if (dev->zoned)
+               if (dev->zoned) {
                        valid_len = null_zone_valid_read_len(nullb,
                                pos >> SECTOR_SHIFT, len);
+                       if (valid_len != len)
+                               valid_len -= (pos & (SECTOR_SIZE - 1));
+               }

                if (valid_len) {
                        copy_from_nullb(nullb, p, pos, valid_len);
--