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prionPRIOn knowledge basePRION:CVE-2020-29569
HistoryDec 15, 2020 - 5:15 p.m.

Null pointer dereference

2020-12-1517:15:00
PRIOn knowledge base
www.prio-n.com
10

8.2 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

14.2%

An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.