ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | unaffected |
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| Linux | Linux | unaffected |
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Configuration 1 [-]
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| Package | CPE | Advisory | Released Date |
|---|---|---|---|
| Red Hat Enterprise Linux 8 | |||
| kernel-0:4.18.0-425.3.1.el8 | cpe:/o:redhat:enterprise_linux:8 | RHSA-2022:7683 | 2022-11-08T00:00:00Z |
| Red Hat Enterprise Linux 9 | |||
| kernel-0:5.14.0-162.6.1.el9_1 | cpe:/a:redhat:enterprise_linux:9 | RHSA-2022:8267 | 2022-11-15T00:00:00Z |
| kernel-0:5.14.0-162.6.1.el9_1 | cpe:/o:redhat:enterprise_linux:9 | RHSA-2022:8267 | 2022-11-15T00:00:00Z |
No data available yet.
| Source | ID | Title |
|---|---|---|
EUVD |
EUVD-2022-54954 | In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock syzbot caught a potential deadlock between the PCM runtime->buffer_mutex and the mm->mmap_lock. It was brought by the recent fix to cover the racy read/write and other ioctls, and in that commit, I overlooked a (hopefully only) corner case that may take the revert lock, namely, the OSS mmap. The OSS mmap operation exceptionally allows to re-configure the parameters inside the OSS mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the copy_from/to_user calls at read/write operations also take the mm->mmap_lock internally, hence it may lead to a AB/BA deadlock. A similar problem was already seen in the past and we fixed it with a refcount (in commit b248371628aa). The former fix covered only the call paths with OSS read/write and OSS ioctls, while we need to cover the concurrent access via both ALSA and OSS APIs now. This patch addresses the problem above by replacing the buffer_mutex lock in the read/write operations with a refcount similar as we've used for OSS. The new field, runtime->buffer_accessing, keeps the number of concurrent read/write operations. Unlike the former buffer_mutex protection, this protects only around the copy_from/to_user() calls; the other codes are basically protected by the PCM stream lock. The refcount can be a negative, meaning blocked by the ioctls. If a negative value is seen, the read/write aborts with -EBUSY. In the ioctl side, OTOH, they check this refcount, too, and set to a negative value for blocking unless it's already being accessed. |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.204% probability within 30 days)
Key SSVC decision points have not yet been added.
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-667 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:5.10.109:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15.32:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16.18:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.17.1:*:*:*:*:*:*:* |
|
| Vendors & Products |
Linux
Linux linux Kernel |
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat enterprise Linux |
|
| CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9 |
|
| Vendors & Products |
Redhat
Redhat enterprise Linux |
| Type | Values Removed | Values Added |
|---|---|---|
| References |
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| Metrics |
threat_severity
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cvssV3_1
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| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock syzbot caught a potential deadlock between the PCM runtime->buffer_mutex and the mm->mmap_lock. It was brought by the recent fix to cover the racy read/write and other ioctls, and in that commit, I overlooked a (hopefully only) corner case that may take the revert lock, namely, the OSS mmap. The OSS mmap operation exceptionally allows to re-configure the parameters inside the OSS mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the copy_from/to_user calls at read/write operations also take the mm->mmap_lock internally, hence it may lead to a AB/BA deadlock. A similar problem was already seen in the past and we fixed it with a refcount (in commit b248371628aa). The former fix covered only the call paths with OSS read/write and OSS ioctls, while we need to cover the concurrent access via both ALSA and OSS APIs now. This patch addresses the problem above by replacing the buffer_mutex lock in the read/write operations with a refcount similar as we've used for OSS. The new field, runtime->buffer_accessing, keeps the number of concurrent read/write operations. Unlike the former buffer_mutex protection, this protects only around the copy_from/to_user() calls; the other codes are basically protected by the PCM stream lock. The refcount can be a negative, meaning blocked by the ioctls. If a negative value is seen, the read/write aborts with -EBUSY. In the ioctl side, OTOH, they check this refcount, too, and set to a negative value for blocking unless it's already being accessed. | |
| Title | ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock | |
| References |
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