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CVE-2021-47290

scsi: target: Fix NULL dereference on XCOPY completion

MEDIUM
5.5
CVSS Score
Published: May 21, 2024 at 02:35 PM UTC
Updated: August 5, 2026 at 09:24 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: target: Fix NULL dereference on XCOPY completion CPU affinity control added with commit 39ae3edda325 ("scsi: target: core: Make completion affinity configurable") makes target_complete_cmd() queue work on a CPU based on se_tpg->se_tpg_wwn->cmd_compl_affinity state. LIO's EXTENDED COPY worker is a special case in that read/write cmds are dispatched using the global xcopy_pt_tpg, which carries a NULL se_tpg_wwn pointer following initialization in target_xcopy_setup_pt(). The NULL xcopy_pt_tpg->se_tpg_wwn pointer is dereferenced on completion of any EXTENDED COPY initiated read/write cmds. E.g using the libiscsi SCSI.ExtendedCopy.Simple test: BUG: kernel NULL pointer dereference, address: 00000000000001a8 RIP: 0010:target_complete_cmd+0x9d/0x130 [target_core_mod] Call Trace: fd_execute_rw+0x148/0x42a [target_core_file] ? __dynamic_pr_debug+0xa7/0xe0 ? target_check_reservation+0x5b/0x940 [target_core_mod] __target_execute_cmd+0x1e/0x90 [target_core_mod] transport_generic_new_cmd+0x17c/0x330 [target_core_mod] target_xcopy_issue_pt_cmd+0x9/0x60 [target_core_mod] target_xcopy_read_source.isra.7+0x10b/0x1b0 [target_core_mod] ? target_check_fua+0x40/0x40 [target_core_mod] ? transport_complete_task_attr+0x130/0x130 [target_core_mod] target_xcopy_do_work+0x61f/0xc00 [target_core_mod] This fix makes target_complete_cmd() queue work on se_cmd->cpuid if se_tpg_wwn is NULL.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel· Linux
95%
5.13 ≤ v < 5.13.65.13 ≤ v < 5.1439ae3edda325e9cf9e978c9788affe88231f3b345.14 rc15.14 rc2
Vendor states this is fixed in a47fa41381a09e5997afd762664db4f5f6657e03 (fixed)
Vendor states this is fixed in e7732c5a19a15a62b0b23fd683a639b0483e1f40 (fixed)
Vendor states this is fixed in 5.13 (unaffected)
Vendor states this is fixed in 5.13.6 (unaffected)
Vendor states this is fixed in 5.14 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/a47fa41381a09e5997afd762664db4f5f6657e03
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/e7732c5a19a15a62b0b23fd683a639b0483e1f40

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.5MEDIUM[email protected]
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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