[PATCH v4 1/1] block: bugfix for Amiga partition overflow check patch

[Michael Schmitz <schmitzmic@gmail.com>]

Making 'blk' sector_t (i.e. 64 bit if LBD support is active)
fails the 'blk>0' test in the partition block loop if a
value of (signed int) -1 is used to mark the end of the
partition block list.

This bug was introduced in patch 3 of my prior Amiga partition
support fixes series, and spotted by Christian Zigotzky when
testing the latest block updates.

Explicitly cast 'blk' to signed int to allow use of -1 to
terminate the partition block linked list.

Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Fixes: b6f3f28f60 ("block: add overflow checks for Amiga partition support")
Message-ID: 024ce4fa-cc6d-50a2-9aae-3701d0ebf668@xenosoft.de
Cc: <stable@vger.kernel.org> # 5.2
Link: https://lore.kernel.org/r/024ce4fa-cc6d-50a2-9aae-3701d0ebf668@xenosoft.de
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
Reviewed-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>

--

Changes since v1:

- corrected Fixes: tag
- added Tested-by:
- reworded commit message to describe filesystem partition
  size mismatch problem

Changes since v2:

Adrian Glaubitz:
- fix typo in commit message

Changes since v3:

Greg KH:
- fix stable tag

Geert Uytterhoeven:
- revert changes to commit message since v1
---
 block/partitions/amiga.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
index ed222b9c901b..506921095412 100644
--- a/block/partitions/amiga.c
+++ b/block/partitions/amiga.c
@@ -90,7 +90,7 @@ int amiga_partition(struct parsed_partitions *state)
 	}
 	blk = be32_to_cpu(rdb->rdb_PartitionList);
 	put_dev_sector(sect);
-	for (part = 1; blk>0 && part<=16; part++, put_dev_sector(sect)) {
+	for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {
 		/* Read in terms partition table understands */
 		if (check_mul_overflow(blk, (sector_t) blksize, &blk)) {
 			pr_err("Dev %s: overflow calculating partition block %llu! Skipping partitions %u and beyond\n",
-- 
2.17.1