scsi: target: core: Fix integer overflow in UNMAP bounds check

[ Upstream commit 2bf2d65 ]

sbc_execute_unmap() checks LBA + range does not exceed the device capacity,
but does not guard against LBA + range wrapping around on 64-bit overflow.

Add an overflow check matching the pattern already used for WRITE_SAME in
the same file.

Fixes: 86d7182 ("target: Add sbc_execute_unmap() helper")
Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://patch.msgid.link/SYBPR01MB7881593C61AD52C69FBDB0BDAF7CA@SYBPR01MB7881.ausprd01.prod.outlook.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: avasummer

drivers/target/target_core_sbc.c

@@ -1136,7 +1136,8 @@ sbc_execute_unmap(struct se_cmd *cmd)
 			goto err;
 		}
 
-		if (lba + range > dev->transport->get_blocks(dev) + 1) {
+		if (lba + range < lba ||
+		    lba + range > dev->transport->get_blocks(dev) + 1) {
 			ret = TCM_ADDRESS_OUT_OF_RANGE;
 			goto err;
 		}