CVE - CVE-2021-47396

CVE-ID
CVE-2021-47396	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: mac80211-hwsim: fix late beacon hrtimer handling Thomas explained in https://lore.kernel.org/r/87mtoeb4hb.ffs@tglx that our handling of the hrtimer here is wrong: If the timer fires late (e.g. due to vCPU scheduling, as reported by Dmitry/syzbot) then it tries to actually rearm the timer at the next deadline, which might be in the past already: 1 2 3 N N+1 \| \| \| ... \| \| ^ intended to fire here (1) ^ next deadline here (2) ^ actually fired here The next time it fires, it's later, but will still try to schedule for the next deadline (now 3), etc. until it catches up with N, but that might take a long time, causing stalls etc. Now, all of this is simulation, so we just have to fix it, but note that the behaviour is wrong even per spec, since there's no value then in sending all those beacons unaligned - they should be aligned to the TBTT (1, 2, 3, ... in the picture), and if we're a bit (or a lot) late, then just resume at that point. Therefore, change the code to use hrtimer_forward_now() which will ensure that the next firing of the timer would be at N+1 (in the picture), i.e. the next interval point after the current time.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/2c204cf594df3b9468368dc9d0b24d482d93cda7 URL:https://git.kernel.org/stable/c/2c204cf594df3b9468368dc9d0b24d482d93cda7 MISC:https://git.kernel.org/stable/c/313bbd1990b6ddfdaa7da098d0c56b098a833572 URL:https://git.kernel.org/stable/c/313bbd1990b6ddfdaa7da098d0c56b098a833572 MISC:https://git.kernel.org/stable/c/9bee85de2c8155388c09a2e1530a243ec1c96f05 URL:https://git.kernel.org/stable/c/9bee85de2c8155388c09a2e1530a243ec1c96f05 MISC:https://git.kernel.org/stable/c/ed2adf69e29848d1eb9df99633dde655421c92ed URL:https://git.kernel.org/stable/c/ed2adf69e29848d1eb9df99633dde655421c92ed
Assigning CNA
kernel.org
Date Record Created
20240521	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240521)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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