ALSA: ctxfi: Limit PTP to a single page
Commit 391e69143d0a increased CT_PTP_NUM from 1 to 4 to support 256
playback streams, but the additional pages are not used by the card
correctly. The CT20K2 hardware already has multiple VMEM_PTPAL
registers, but using them separately would require refactoring the
entire virtual memory allocation logic.
ct_vm_map() always uses PTEs in vm->ptp[0].area regardless of
CT_PTP_NUM. On AMD64 systems, a single PTP covers 512 PTEs (2M). When
aggregate memory allocations exceed this limit, ct_vm_map() tries to
access beyond the allocated space and causes a page fault:
BUG: unable to handle page fault for address: ffffd4ae8a10a000
Oops: Oops: 0002 [#1] SMP PTI
RIP: 0010:ct_vm_map+0x17c/0x280 [snd_ctxfi]
Call Trace:
atc_pcm_playback_prepare+0x225/0x3b0
ct_pcm_playback_prepare+0x38/0x60
snd_pcm_do_prepare+0x2f/0x50
snd_pcm_action_single+0x36/0x90
snd_pcm_action_nonatomic+0xbf/0xd0
snd_pcm_ioctl+0x28/0x40
__x64_sys_ioctl+0x97/0xe0
do_syscall_64+0x81/0x610
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Revert CT_PTP_NUM to 1. The 256 SRC_RESOURCE_NUM and playback_count
remain unchanged.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Debian DSA |
DSA-6238-1 | linux security update |
Wed, 29 Apr 2026 20:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | NVD-CWE-noinfo |
Mon, 27 Apr 2026 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Mon, 27 Apr 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Mon, 27 Apr 2026 11:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Sat, 25 Apr 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-788 | |
| References |
|
Fri, 24 Apr 2026 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ALSA: ctxfi: Limit PTP to a single page Commit 391e69143d0a increased CT_PTP_NUM from 1 to 4 to support 256 playback streams, but the additional pages are not used by the card correctly. The CT20K2 hardware already has multiple VMEM_PTPAL registers, but using them separately would require refactoring the entire virtual memory allocation logic. ct_vm_map() always uses PTEs in vm->ptp[0].area regardless of CT_PTP_NUM. On AMD64 systems, a single PTP covers 512 PTEs (2M). When aggregate memory allocations exceed this limit, ct_vm_map() tries to access beyond the allocated space and causes a page fault: BUG: unable to handle page fault for address: ffffd4ae8a10a000 Oops: Oops: 0002 [#1] SMP PTI RIP: 0010:ct_vm_map+0x17c/0x280 [snd_ctxfi] Call Trace: atc_pcm_playback_prepare+0x225/0x3b0 ct_pcm_playback_prepare+0x38/0x60 snd_pcm_do_prepare+0x2f/0x50 snd_pcm_action_single+0x36/0x90 snd_pcm_action_nonatomic+0xbf/0xd0 snd_pcm_ioctl+0x28/0x40 __x64_sys_ioctl+0x97/0xe0 do_syscall_64+0x81/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e Revert CT_PTP_NUM to 1. The 256 SRC_RESOURCE_NUM and playback_count remain unchanged. | |
| Title | ALSA: ctxfi: Limit PTP to a single page | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T22:11:57.946Z
Reserved: 2026-03-09T15:48:24.121Z
Link: CVE-2026-31602
No data.
Status : Analyzed
Published: 2026-04-24T15:16:39.263
Modified: 2026-04-29T20:16:49.660
Link: CVE-2026-31602
OpenCVE Enrichment
Updated: 2026-04-30T04:15:26Z
Debian DSA