Subject: CVE-2021-47580: scsi: scsi_debug: Fix type in min_t to avoid stack OOB

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

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

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

The Linux kernel CVE team has assigned CVE-2021-47580 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.10.88 with commit bdb854f134b9
	Fixed in 5.15.11 with commit 308514764593
	Fixed in 5.16 with commit 36e07d7ede88

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47580
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/scsi/scsi_debug.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/bdb854f134b964528fa543e0351022eb45bd7346
	https://git.kernel.org/stable/c/3085147645938eb41f0bc0e25ef9791e71f5ee4b
	https://git.kernel.org/stable/c/36e07d7ede88a1f1ef8f0f209af5b7612324ac2c