scsi: scsi_debug: Fix type in min_t to avoid stack OOB

scsi: scsi_debug: Fix type in min_t to avoid stack OOB

commit 36e07d7ede88a1f1ef8f0f209af5b7612324ac2c upstream.

Change min_t() to use type "u32" instead of type "int" to avoid stack out
of bounds. With min_t() type "int" the values get sign extended and the
larger value gets used causing stack out of bounds.

BUG: KASAN: stack-out-of-bounds in memcpy include/linux/fortify-string.h:191 [inline]
BUG: KASAN: stack-out-of-bounds in sg_copy_buffer+0x1de/0x240 lib/scatterlist.c:976
Read of size 127 at addr ffff888072607128 by task syz-executor.7/18707

CPU: 1 PID: 18707 Comm: syz-executor.7 Not tainted 5.15.0-syzk #1
Hardware name: Red Hat KVM, BIOS 1.13.0-2
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106
 print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold.14+0x7d/0x117 mm/kasan/report.c:459
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x1a3/0x210 mm/kasan/generic.c:189
 memcpy+0x23/0x60 mm/kasan/shadow.c:65
 memcpy include/linux/fortify-string.h:191 [inline]
 sg_copy_buffer+0x1de/0x240 lib/scatterlist.c:976
 sg_copy_from_buffer+0x33/0x40 lib/scatterlist.c:1000
 fill_from_dev_buffer.part.34+0x82/0x130 drivers/scsi/scsi_debug.c:1162
 fill_from_dev_buffer drivers/scsi/scsi_debug.c:1888 [inline]
 resp_readcap16+0x365/0x3b0 drivers/scsi/scsi_debug.c:1887
 schedule_resp+0x4d8/0x1a70 drivers/scsi/scsi_debug.c:5478
 scsi_debug_queuecommand+0x8c9/0x1ec0 drivers/scsi/scsi_debug.c:7533
 scsi_dispatch_cmd drivers/scsi/scsi_lib.c:1520 [inline]
 scsi_queue_rq+0x16b0/0x2d40 drivers/scsi/scsi_lib.c:1699
 blk_mq_dispatch_rq_list+0xb9b/0x2700 block/blk-mq.c:1639
 __blk_mq_sched_dispatch_requests+0x28f/0x590 block/blk-mq-sched.c:325
 blk_mq_sched_dispatch_requests+0x105/0x190 block/blk-mq-sched.c:358
 __blk_mq_run_hw_queue+0xe5/0x150 block/blk-mq.c:1761
 __blk_mq_delay_run_hw_queue+0x4f8/0x5c0 block/blk-mq.c:1838
 blk_mq_run_hw_queue+0x18d/0x350 block/blk-mq.c:1891
 blk_mq_sched_insert_request+0x3db/0x4e0 block/blk-mq-sched.c:474
 blk_execute_rq_nowait+0x16b/0x1c0 block/blk-exec.c:62
 sg_common_write.isra.18+0xeb3/0x2000 drivers/scsi/sg.c:836
 sg_new_write.isra.19+0x570/0x8c0 drivers/scsi/sg.c:774
 sg_ioctl_common+0x14d6/0x2710 drivers/scsi/sg.c:939
 sg_ioctl+0xa2/0x180 drivers/scsi/sg.c:1165
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Link: https://lore.kernel.org/r/1636484247-21254-1-git-send-email-george.kennedy@oracle.com
Reported-by: syzkaller <syzkaller@googlegroups.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>