cbcvebase.
CVE-2021-46988
published 2024-02-28

CVE-2021-46988: 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…

PriorityP417medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.24%
15.2th percentile
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.

Affected

20 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.10.38-1 (bookworm)linux 5.10.38-1 (bookworm)
linuxlinux——
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < 319116227e52d49eee671f0aa278bac89b3c1b69319116227e52d49eee671f0aa278bac89b3c1b69
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < 07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < 140cfd9980124aecb6c03ef2e69c72d0548744de140cfd9980124aecb6c03ef2e69c72d0548744de
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < ad53127973034c63b5348715a1043d0e80ceb330ad53127973034c63b5348715a1043d0e80ceb330
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < 2d59a0ed8b26b8f3638d8afc31f839e27759f1f62d59a0ed8b26b8f3638d8afc31f839e27759f1f6
linuxlinux>= cb658a453b9327ce96ce5222c24d162b5b65b564 < 7ed9d238c7dbb1fdb63ad96a6184985151b0171c7ed9d238c7dbb1fdb63ad96a6184985151b0171c
linuxlinux_kernel——
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 4.11 < 4.14.2334.14.233
linuxlinux_kernel>= 4.15 < 4.19.1914.19.191
linuxlinux_kernel>= 4.20 < 5.4.1205.4.120
linuxlinux_kernel>= 5.11 < 5.11.225.11.22
linuxlinux_kernel>= 5.12 < 5.12.55.12.5
linuxlinux_kernel>= 5.5 < 5.10.385.10.38

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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