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CVE Record

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

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

MediumCVSS 6.6Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel issue in the SCSI debug driver. A type mismatch can make the kernel copy more data than intended, causing a stack out-of-bounds read. It requires local access with low privileges, so business urgency is mainly for exposed multi-user Linux systems and environments where the affected driver is present.

Executive priority

Medium priority. This is not supported as actively exploited or remotely reachable from the supplied evidence, but it is a kernel memory-safety issue with high confidentiality impact. Patch through normal kernel maintenance, with faster handling for shared Linux systems.

Technical view

The flaw is in drivers/scsi/scsi_debug.c. Using min_t() with int caused sign extension, selecting a larger value and triggering stack out-of-bounds reads in memcpy through sg_copy_buffer and scsi_debug response handling. CVSS 3.1 is 6.6 with local attack vector, low complexity, low privileges, no user interaction, and high confidentiality impact.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions where the scsi_debug code path is present and reachable. The CVE record lists Linux kernel versions including 5.8, 5.10.88, 5.15.11, and 5.16 as affected, with stable kernel commits referenced as fixes.

Exploitation context

The supplied sources do not report active exploitation, and the CVE is not listed as KEV. The stack trace came from KASAN/syzkaller-style kernel testing. Treat this as a local kernel memory-safety bug requiring host access, not a remotely exploitable internet-facing flaw based on available evidence.

Researcher notes

Focus validation on kernel version, distribution backport status, and scsi_debug reachability. The public record identifies the fix as changing min_t() to use u32 to avoid sign extension. Do not assume broader SCSI driver impact beyond the named scsi_debug path without vendor confirmation.

Mitigation direction

  • Review vendor kernel advisories for fixed packages matching the referenced stable commits.
  • Update affected Linux kernels through the normal distribution or kernel vendor channel.
  • Check whether scsi_debug is available or loaded on production systems.
  • Restrict local shell access on sensitive systems until patch status is confirmed.
  • Prioritize shared hosts, build systems, and multi-tenant Linux environments.

Validation and detection

  • Inventory Linux kernel versions across servers and endpoints.
  • Confirm whether scsi_debug is built, installed, or loaded.
  • Map running kernels to vendor advisories or the referenced stable commits.
  • Review local-user exposure on systems that cannot be patched quickly.
  • Track whether distribution backports include this specific fix.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-47580 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.6 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.6CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L1.84.7CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

6.6Medium
CVSS 3.1 vector shape for CVE-2021-47580Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux87c715dcde633f4cc4690a24a240e838181e6a9d, 87c715dcde633f4cc4690a24a240e838181e6a9d, 87c715dcde633f4cc4690a24a240e838181e6a9dunaffected
LinuxLinux5.8, 0, 5.10.88, 5.15.11, 5.16affected
Weakness

CWE details

No CWE listed

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