CVE-2021-47603: In the Linux kernel, the following vulnerability has been resolved: audit: improve robustness of the audit queue handling If the audit daemon were ever to get…

PriorityP416medium4.4CVSS 3.1

AVLACLPRHUINSUCNINAH

EPSS

0.18%

7.7th percentile

In the Linux kernel, the following vulnerability has been resolved: audit: improve robustness of the audit queue handling If the audit daemon were ever to get stuck in a stopped state the kernel's kauditd_thread() could get blocked attempting to send audit records to the userspace audit daemon. With the kernel thread blocked it is possible that the audit queue could grow unbounded as certain audit record generating events must be exempt from the queue limits else the system enter a deadlock state. This patch resolves this problem by lowering the kernel thread's socket sending timeout from MAX_SCHEDULE_TIMEOUT to HZ/10 and tweaks the kauditd_send_queue() function to better manage the various audit queues when connection problems occur between the kernel and the audit daemon. With this patch, the backlog may temporarily grow beyond the defined limits when the audit daemon is stopped and the system is under heavy audit pressure, but kauditd_thread() will continue to make progress and drain the queues as it would for other connection problems. For example, with the audit daemon put into a stopped state and the system configured to audit every syscall it was still possible to shutdown the system without a kernel panic, deadlock, etc.; granted, the system was slow to shutdown but that is to be expected given the extreme pressure of recording every syscall. The timeout value of HZ/10 was chosen primarily through experimentation and this developer's "gut feeling". There is likely no one perfect value, but as this scenario is limited in scope (root privileges would be needed to send SIGSTOP to the audit daemon), it is likely not worth exposing this as a tunable at present. This can always be done at a later date if it proves necessary.

Affected

21 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 5.15.15-1 (bookworm)	linux 5.15.15-1 (bookworm)
linux	linux	—	—
linux	linux	—	—
linux	linux	>= 4.10.7 < 4.11	4.11
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < 75fdb751f84727d614deea0571a1490c3225d83a	75fdb751f84727d614deea0571a1490c3225d83a
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < 8389f50ceb854cb437fefb9330d5024ed3c7c1f5	8389f50ceb854cb437fefb9330d5024ed3c7c1f5
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < 0d3277eabd542fb662be23696e5ec9f390d688e1	0d3277eabd542fb662be23696e5ec9f390d688e1
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < 4cc6badff97f74d0fce65f9784b5df3b64e4250b	4cc6badff97f74d0fce65f9784b5df3b64e4250b
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < a5f4d17daf2e6cd7c1d9676b476147f6b4ac53f2	a5f4d17daf2e6cd7c1d9676b476147f6b4ac53f2
linux	linux	>= 5b52330bbfe63b3305765354d6046c9f7f89c011 < f4b3ee3c85551d2d343a3ba159304066523f730f	f4b3ee3c85551d2d343a3ba159304066523f730f
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 5.10.92-1	5.10.92-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 0 < 5.15.15-1	5.15.15-1
linux	linux_kernel	>= 4.10.7 < 4.11	4.11
linux	linux_kernel	>= 4.11 < 4.14.259	4.14.259
linux	linux_kernel	>= 4.15 < 4.19.222	4.19.222
linux	linux_kernel	>= 4.20 < 5.4.168	5.4.168
linux	linux_kernel	>= 5.11 < 5.15.11	5.15.11
linux	linux_kernel	>= 5.5 < 5.10.88	5.10.88

CVSS provenance

nvdv3.14.4MEDIUMCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

osv4.4MEDIUM

vendor_debian4.4MEDIUM

vendor_redhat4.4MEDIUM

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