In the Linux kernel, the following vulnerability has been resolved: io_uring/rw: fix missing NOWAIT check for O_DIRECT start write When io_uring starts a write, it'll call kiocb_start_write() to bump the super block rwsem, preventing any freezes from happening while that write is in-flight. The freeze side will grab that rwsem for writing, excluding any new writers from happening and waiting for existing writes to finish. But io_uring unconditionally uses kiocb_start_write(), which will block if someone is currently attempting to freeze the mount point. This causes a deadlock where freeze is waiting for previous writes to complete, but the previous writes cannot complete, as the task that is supposed to complete them is blocked waiting on starting a new write. This results in the following stuck trace showing that dependency with the write blocked starting a new write: task:fio state:D stack:0 pid:886 tgid:886 ppid:876 Call trace: __switch_to+0x1d8/0x348 __schedule+0x8e8/0x2248 schedule+0x110/0x3f0 percpu_rwsem_wait+0x1e8/0x3f8 __percpu_down_read+0xe8/0x500 io_write+0xbb8/0xff8 io_issue_sqe+0x10c/0x1020 io_submit_sqes+0x614/0x2110 __arm64_sys_io_uring_enter+0x524/0x1038 invoke_syscall+0x74/0x268 el0_svc_common.constprop.0+0x160/0x238 do_el0_svc+0x44/0x60 el0_svc+0x44/0xb0 el0t_64_sync_handler+0x118/0x128 el0t_64_sync+0x168/0x170 INFO: task fsfreeze:7364 blocked for more than 15 seconds. Not tainted 6.12.0-rc5-00063-g76aaf945701c #7963 with the attempting freezer stuck trying to grab the rwsem: task:fsfreeze state:D stack:0 pid:7364 tgid:7364 ppid:995 Call trace: __switch_to+0x1d8/0x348 __schedule+0x8e8/0x2248 schedule+0x110/0x3f0 percpu_down_write+0x2b0/0x680 freeze_super+0x248/0x8a8 do_vfs_ioctl+0x149c/0x1b18 __arm64_sys_ioctl+0xd0/0x1a0 invoke_syscall+0x74/0x268 el0_svc_common.constprop.0+0x160/0x238 do_el0_svc+0x44/0x60 el0_svc+0x44/0xb0 el0t_64_sync_handler+0x118/0x128 el0t_64_sync+0x168/0x170 Fix this by having the io_uring side honor IOCB_NOWAIT, and only attempt a blocking grab of the super block rwsem if it isn't set. For normal issue where IOCB_NOWAIT would always be set, this returns -EAGAIN which will have io_uring core issue a blocking attempt of the write. That will in turn also get completions run, ensuring forward progress. Since freezing requires CAP_SYS_ADMIN in the first place, this isn't something that can be triggered by a regular user.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-5818 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-5818-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     November 24, 2024                     https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : linux     CVE ID         : CVE-2022-45888 CVE-2023-52812 CVE-2024-26952 CVE-2024-26954                      CVE-2024-35964 CVE-2024-36244 CVE-2024-36478 CVE-2024-36914                      CVE-2024-36915 CVE-2024-36923 CVE-2024-38540 CVE-2024-38553                      CVE-2024-41080 CVE-2024-42322 CVE-2024-43868 CVE-2024-43904                      CVE-2024-43911 CVE-2024-44949 CVE-2024-49950 CVE-2024-49960                      CVE-2024-49974 CVE-2024-49986 CVE-2024-49991 CVE-2024-50012                      CVE-2024-50036 CVE-2024-50067 CVE-2024-50072 CVE-2024-50126                      CVE-2024-50215 CVE-2024-50218 CVE-2024-50228 CVE-2024-50229                      CVE-2024-50230 CVE-2024-50232 CVE-2024-50233 CVE-2024-50234                      CVE-2024-50235 CVE-2024-50236 CVE-2024-50237 CVE-2024-50242                      CVE-2024-50243 CVE-2024-50244 CVE-2024-50245 CVE-2024-50247                      CVE-2024-50249 CVE-2024-50250 CVE-2024-50251 CVE-2024-50252                      CVE-2024-50255 CVE-2024-50256 CVE-2024-50257 CVE-2024-50259                      CVE-2024-50261 CVE-2024-50262 CVE-2024-50264 CVE-2024-50265                      CVE-2024-50267 CVE-2024-50268 CVE-2024-50269 CVE-2024-50271                      CVE-2024-50272 CVE-2024-50273 CVE-2024-50276 CVE-2024-50278                      CVE-2024-50279 CVE-2024-50280 CVE-2024-50282 CVE-2024-50283                      CVE-2024-50284 CVE-2024-50286 CVE-2024-50287 CVE-2024-50290                      CVE-2024-50292 CVE-2024-50295 CVE-2024-50296 CVE-2024-50299                      CVE-2024-50301 CVE-2024-50302 CVE-2024-53042 CVE-2024-53043                      CVE-2024-53052 CVE-2024-53054 CVE-2024-53055 CVE-2024-53057                      CVE-2024-53058 CVE-2024-53059 CVE-2024-53060 CVE-2024-53061                      CVE-2024-53063 CVE-2024-53066 CVE-2024-53070 CVE-2024-53072                      CVE-2024-53081 CVE-2024-53082 CVE-2024-53088 CVE-2024-53093

    Several vulnerabilities have been discovered in the Linux kernel that     may lead to a privilege escalation, denial of service or information     leaks.

    For the stable distribution (bookworm), these problems have been fixed in     version 6.1.119-1.

    We recommend that you upgrade your linux packages.

    For the detailed security status of linux please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/linux

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

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