Description
In the Linux kernel, the following vulnerability has been resolved:
drm/panthor: Be stricter about IO mapping flags
The current panthor_device_mmap_io() implementation has two issues:
1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET,
panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear
VM_MAYWRITE. That means userspace can use mprotect() to make the mapping
writable later on. This is a classic Linux driver gotcha.
I don't think this actually has any impact in practice:
When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and
when the GPU is not powered, the dummy_latest_flush page provided by the
driver is deliberately designed to not do any flushes, so the only thing
writing to the dummy_latest_flush could achieve would be to make *more*
flushes happen.
2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are
mappings without the VM_SHARED flag).
MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has
copy-on-write semantics, which for VM_PFNMAP are semi-supported but
fairly cursed.
In particular, in such a mapping, the driver can only install PTEs
during mmap() by calling remap_pfn_range() (because remap_pfn_range()
wants to **store the physical address of the mapped physical memory into
the vm_pgoff of the VMA**); installing PTEs later on with a fault
handler (as panthor does) is not supported in private mappings, and so
if you try to fault in such a mapping, vmf_insert_pfn_prot() splats when
it hits a BUG() check.
Fix it by clearing the VM_MAYWRITE flag (userspace writing to the FLUSH_ID
doesn't make sense) and requiring VM_SHARED (copy-on-write semantics for
the FLUSH_ID don't make sense).
Reproducers for both scenarios are in the notes of my patch on the mailing
list; I tested that these bugs exist on a Rock 5B machine.
Note that I only compile-tested the patch, I haven't tested it; I don't
have a working kernel build setup for the test machine yet. Please test it
before applying it.
drm/panthor: Be stricter about IO mapping flags
The current panthor_device_mmap_io() implementation has two issues:
1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET,
panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear
VM_MAYWRITE. That means userspace can use mprotect() to make the mapping
writable later on. This is a classic Linux driver gotcha.
I don't think this actually has any impact in practice:
When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and
when the GPU is not powered, the dummy_latest_flush page provided by the
driver is deliberately designed to not do any flushes, so the only thing
writing to the dummy_latest_flush could achieve would be to make *more*
flushes happen.
2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are
mappings without the VM_SHARED flag).
MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has
copy-on-write semantics, which for VM_PFNMAP are semi-supported but
fairly cursed.
In particular, in such a mapping, the driver can only install PTEs
during mmap() by calling remap_pfn_range() (because remap_pfn_range()
wants to **store the physical address of the mapped physical memory into
the vm_pgoff of the VMA**); installing PTEs later on with a fault
handler (as panthor does) is not supported in private mappings, and so
if you try to fault in such a mapping, vmf_insert_pfn_prot() splats when
it hits a BUG() check.
Fix it by clearing the VM_MAYWRITE flag (userspace writing to the FLUSH_ID
doesn't make sense) and requiring VM_SHARED (copy-on-write semantics for
the FLUSH_ID don't make sense).
Reproducers for both scenarios are in the notes of my patch on the mailing
list; I tested that these bugs exist on a Rock 5B machine.
Note that I only compile-tested the patch, I haven't tested it; I don't
have a working kernel build setup for the test machine yet. Please test it
before applying it.
No analysis available yet.
Remediation
No remediation available yet.
Tracking
Sign in to view the affected projects.
Advisories
| Source | ID | Title |
|---|---|---|
Ubuntu USN |
USN-7276-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7277-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7310-1 | Linux kernel vulnerabilities |
References
History
Thu, 13 Feb 2025 00:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-285 |
Tue, 26 Nov 2024 22:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | NVD-CWE-noinfo | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.12:rc6:*:*:*:*:*:* |
|
| Vendors & Products |
Linux
Linux linux Kernel |
Fri, 22 Nov 2024 14:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Tue, 19 Nov 2024 17:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Be stricter about IO mapping flags The current panthor_device_mmap_io() implementation has two issues: 1. For mapping DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET, panthor_device_mmap_io() bails if VM_WRITE is set, but does not clear VM_MAYWRITE. That means userspace can use mprotect() to make the mapping writable later on. This is a classic Linux driver gotcha. I don't think this actually has any impact in practice: When the GPU is powered, writes to the FLUSH_ID seem to be ignored; and when the GPU is not powered, the dummy_latest_flush page provided by the driver is deliberately designed to not do any flushes, so the only thing writing to the dummy_latest_flush could achieve would be to make *more* flushes happen. 2. panthor_device_mmap_io() does not block MAP_PRIVATE mappings (which are mappings without the VM_SHARED flag). MAP_PRIVATE in combination with VM_MAYWRITE indicates that the VMA has copy-on-write semantics, which for VM_PFNMAP are semi-supported but fairly cursed. In particular, in such a mapping, the driver can only install PTEs during mmap() by calling remap_pfn_range() (because remap_pfn_range() wants to **store the physical address of the mapped physical memory into the vm_pgoff of the VMA**); installing PTEs later on with a fault handler (as panthor does) is not supported in private mappings, and so if you try to fault in such a mapping, vmf_insert_pfn_prot() splats when it hits a BUG() check. Fix it by clearing the VM_MAYWRITE flag (userspace writing to the FLUSH_ID doesn't make sense) and requiring VM_SHARED (copy-on-write semantics for the FLUSH_ID don't make sense). Reproducers for both scenarios are in the notes of my patch on the mailing list; I tested that these bugs exist on a Rock 5B machine. Note that I only compile-tested the patch, I haven't tested it; I don't have a working kernel build setup for the test machine yet. Please test it before applying it. | |
| Title | drm/panthor: Be stricter about IO mapping flags | |
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-10-01T20:17:16.169Z
Reserved: 2024-11-19T17:17:24.976Z
Link: CVE-2024-53071
No data.
Status : Modified
Published: 2024-11-19T18:15:26.793
Modified: 2025-10-01T21:16:25.480
Link: CVE-2024-53071
OpenCVE Enrichment
No data.
Weaknesses
Ubuntu USN