openrisc: signal: do not restore privileged SR bits on sigreturn

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80560
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-26 15:17:10 UTC
Updated2026-08-27 06:17:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: openrisc: signal: do not restore privileged SR bits on sigreturn restore_sigcontext() copies the whole supervision register (SR) from the signal frame and only clears SPR_SR_SM before the value is reloaded into the hardware SR (through ESR and l.rfe) on the return to user space. All other SR bits are left under user control. An unprivileged task can thus return from a signal handler through a crafted sigframe that clears SPR_SR_DME. With the data MMU disabled the CPU performs no translation or protection on data accesses, so the task gains read and write access to arbitrary physical memory, a local privilege escalation. SPR_SR_IME, SPR_SR_SUMRA, SPR_SR_LEE, SPR_SR_EPH and the cache-enable bits are exposed the same way. The ptrace GPR regset already refuses any change to SR for exactly this reason. Restore only the arithmetic flag bits (F, CY, OV) from the signal frame and take every privileged control bit from the SR the kernel saved on signal entry. Verified with qemu-system-or1k -M or1k-sim: before this change an unprivileged PoC clears SPR_SR_DME in rt_sigreturn and writes a marker to physical address 0x03000000 (beyond the kernel's mem=32M); afterwards the same PoC receives SIGSEGV and physical memory is unchanged.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c bc2e24ba6e167ccf374a197457aa5640a802f429 git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c cf1b5514ddf9df098ce7e3741fc9679fd85a4ec6 git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c cd8b43a71755c516f5c1f265a103438ae9ab15be git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c b4d73c3848bae9084fa8b9b2aa76d99a7d8eb17d git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c 89a91b30685c0493b0fa2b47d0ab41061a63069d git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c a88d688be8d7f03cbf927f2ab454ea9fa58d2979 git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c 212fc482ddd7f9ccdd74a05eab1cac849350dcd6 git Not specified
CNA Linux Linux affected ac689eb7f9d4e270d1365853b82eece669387e2c 32ef1b30ad736519f7a207bcc2986f3d4129d972 git Not specified
CNA Linux Linux affected 3.1 Not specified
CNA Linux Linux unaffected 3.1 semver Not specified
CNA Linux Linux unaffected 5.10.266 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.217 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.184 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.153 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.105 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.46 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.10 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a88d688be8d7f03cbf927f2ab454ea9fa58d2979 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b4d73c3848bae9084fa8b9b2aa76d99a7d8eb17d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/32ef1b30ad736519f7a207bcc2986f3d4129d972 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cd8b43a71755c516f5c1f265a103438ae9ab15be 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bc2e24ba6e167ccf374a197457aa5640a802f429 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/212fc482ddd7f9ccdd74a05eab1cac849350dcd6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/89a91b30685c0493b0fa2b47d0ab41061a63069d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cf1b5514ddf9df098ce7e3741fc9679fd85a4ec6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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