In the Linux kernel, the following vulnerability has been resolved:
arm64: io: Reject non-user protection in ioremap_prot()
Mapping a stack-top page via /dev/mem with PROT_NONE and then
reading that process's /proc/<pid>/cmdline triggers a spurious WARN
in ioremap_prot() through generic_access_phys():
WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys
Call trace:
generic_access_phys+0x1c8/0x228 (P)
__access_remote_vm+0x2b4/0x398
access_remote_vm+0x14/0x30
get_mm_cmdline+0xf8/0x2a0
proc_pid_cmdline_read+0x68/0x120
generic_access_phys() passes the protection derived from the user PTE
to ioremap_prot(). On arm64, a PROT_NONE mapping is represented by a
present-invalid PTE, so pte_present() still returns true and the
protection reaches ioremap_prot().
A PROT_NONE mapping does not have PTE_USER, causing the existing
WARN_ON_ONCE() in ioremap_prot() to fire even though this is a valid
user mapping. Execute-only mappings have the same issue and must not
be readable through this path either.
ioremap_prot() should therefore reject protection values without
PTE_USER without warning. This makes the access fail cleanly for
PROT_NONE and execute-only mappings while retaining the existing
user-protection contract.
arm64: io: Reject non-user protection in ioremap_prot()
Mapping a stack-top page via /dev/mem with PROT_NONE and then
reading that process's /proc/<pid>/cmdline triggers a spurious WARN
in ioremap_prot() through generic_access_phys():
WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys
Call trace:
generic_access_phys+0x1c8/0x228 (P)
__access_remote_vm+0x2b4/0x398
access_remote_vm+0x14/0x30
get_mm_cmdline+0xf8/0x2a0
proc_pid_cmdline_read+0x68/0x120
generic_access_phys() passes the protection derived from the user PTE
to ioremap_prot(). On arm64, a PROT_NONE mapping is represented by a
present-invalid PTE, so pte_present() still returns true and the
protection reaches ioremap_prot().
A PROT_NONE mapping does not have PTE_USER, causing the existing
WARN_ON_ONCE() in ioremap_prot() to fire even though this is a valid
user mapping. Execute-only mappings have the same issue and must not
be readable through this path either.
ioremap_prot() should therefore reject protection values without
PTE_USER without warning. This makes the access fail cleanly for
PROT_NONE and execute-only mappings while retaining the existing
user-protection contract.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 23 Oct 2026 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-703 |
Fri, 23 Oct 2026 16:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux linux
|
|
| Vendors & Products |
Linux linux
|
Fri, 23 Oct 2026 12:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: arm64: io: Reject non-user protection in ioremap_prot() Mapping a stack-top page via /dev/mem with PROT_NONE and then reading that process's /proc/<pid>/cmdline triggers a spurious WARN in ioremap_prot() through generic_access_phys(): WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys Call trace: generic_access_phys+0x1c8/0x228 (P) __access_remote_vm+0x2b4/0x398 access_remote_vm+0x14/0x30 get_mm_cmdline+0xf8/0x2a0 proc_pid_cmdline_read+0x68/0x120 generic_access_phys() passes the protection derived from the user PTE to ioremap_prot(). On arm64, a PROT_NONE mapping is represented by a present-invalid PTE, so pte_present() still returns true and the protection reaches ioremap_prot(). A PROT_NONE mapping does not have PTE_USER, causing the existing WARN_ON_ONCE() in ioremap_prot() to fire even though this is a valid user mapping. Execute-only mappings have the same issue and must not be readable through this path either. ioremap_prot() should therefore reject protection values without PTE_USER without warning. This makes the access fail cleanly for PROT_NONE and execute-only mappings while retaining the existing user-protection contract. | |
| Title | arm64: io: Reject non-user protection in ioremap_prot() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-23T12:05:45.179Z
Reserved: 2026-09-25T10:25:14.380Z
Link: CVE-2026-98923
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-23T13:17:12.957
Modified: 2026-10-23T13:17:12.957
Link: CVE-2026-98923
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-10-23T18:00:15Z
Weaknesses