In the Linux kernel, the following vulnerability has been resolved:
userfaultfd: release page in error path to avoid BUG_ON
Consider the following sequence of events:
1. Userspace issues a UFFD ioctl, which ends up calling into
shmem_mfill_atomic_pte(). We successfully account the blocks, we
shmem_alloc_page(), but then the copy_from_user() fails. We return
-ENOENT. We don't release the page we allocated.
2. Our caller detects this error code, tries the copy_from_user() after
dropping the mmap_lock, and retries, calling back into
shmem_mfill_atomic_pte().
3. Meanwhile, let's say another process filled up the tmpfs being used.
4. So shmem_mfill_atomic_pte() fails to account blocks this time, and
immediately returns - without releasing the page.
This triggers a BUG_ON in our caller, which asserts that the page
should always be consumed, unless -ENOENT is returned.
To fix this, detect if we have such a "dangling" page when accounting
fails, and if so, release it before returning.
userfaultfd: release page in error path to avoid BUG_ON
Consider the following sequence of events:
1. Userspace issues a UFFD ioctl, which ends up calling into
shmem_mfill_atomic_pte(). We successfully account the blocks, we
shmem_alloc_page(), but then the copy_from_user() fails. We return
-ENOENT. We don't release the page we allocated.
2. Our caller detects this error code, tries the copy_from_user() after
dropping the mmap_lock, and retries, calling back into
shmem_mfill_atomic_pte().
3. Meanwhile, let's say another process filled up the tmpfs being used.
4. So shmem_mfill_atomic_pte() fails to account blocks this time, and
immediately returns - without releasing the page.
This triggers a BUG_ON in our caller, which asserts that the page
should always be consumed, unless -ENOENT is returned.
To fix this, detect if we have such a "dangling" page when accounting
fails, and if so, release it before returning.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 26 Dec 2024 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:o:linux:linux_kernel:5.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc7:*:*:*:*:*:* |
cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* |
Tue, 24 Dec 2024 14:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:rc7:*:*:*:*:*:* |
|
| Vendors & Products |
Linux
Linux linux Kernel |
Mon, 04 Nov 2024 13:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-04T07:01:49.099Z
Reserved: 2024-02-27T18:42:55.948Z
Link: CVE-2021-46988
Updated: 2024-08-04T05:24:38.475Z
Status : Analyzed
Published: 2024-02-28T09:15:37.640
Modified: 2024-12-26T15:01:37.110
Link: CVE-2021-46988
OpenCVE Enrichment
No data.
Weaknesses