[PATCH v11 03/13] scsi: scsi_debug: Refuse a negative physblk_exp

[Niklas Cassel <cassel@kernel.org>]

sdebug_init() refuses a physblk_exp above 15, but the parameter is a
signed int, so a negative value is accepted. The driver then shifts by
it when it builds the Block Limits VPD page, which is undefined
behaviour, and READ CAPACITY (16) reports an exponent of 15 for -1.

Refuse a negative value as well, and print it as a signed value.

Assisted-by: LLM
Fixes: ea61fca58c13 ("scsi_debug: Add support for physical block exponent and alignment")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
Tested by loading the module with physblk_exp=-1. Before this patch it
loads, and READ CAPACITY (16) reports a logical blocks per physical
block exponent of 15. After it the module is refused with -EINVAL and
"invalid physblk_exp -1".
---
 drivers/scsi/scsi_debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 8e45a57ae406..f7c71fcc53fd 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -8656,8 +8656,8 @@ static int __init scsi_debug_init(void)
 		return -EINVAL;
 	}
 
-	if (sdebug_physblk_exp > 15) {
-		pr_err("invalid physblk_exp %u\n", sdebug_physblk_exp);
+	if (sdebug_physblk_exp < 0 || sdebug_physblk_exp > 15) {
+		pr_err("invalid physblk_exp %d\n", sdebug_physblk_exp);
 		return -EINVAL;
 	}
 
-- 
2.55.0