CVE-2021-47396
published 2024-05-21CVE-2021-47396: In the Linux kernel, the following vulnerability has been resolved: mac80211-hwsim: fix late beacon hrtimer handling Thomas explained in…
PriorityP419medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.24%
15.0th percentile
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.
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 5.14.12-1 (bookworm) | linux 5.14.12-1 (bookworm) |
| linux | linux | — | — |
| linux | linux | >= 01e59e467ecf976c782eecd4dc99644802cc60e2 < 9bee85de2c8155388c09a2e1530a243ec1c96f05 | 9bee85de2c8155388c09a2e1530a243ec1c96f05 |
| linux | linux | >= 01e59e467ecf976c782eecd4dc99644802cc60e2 < 2c204cf594df3b9468368dc9d0b24d482d93cda7 | 2c204cf594df3b9468368dc9d0b24d482d93cda7 |
| linux | linux | >= 01e59e467ecf976c782eecd4dc99644802cc60e2 < ed2adf69e29848d1eb9df99633dde655421c92ed | ed2adf69e29848d1eb9df99633dde655421c92ed |
| linux | linux | >= 01e59e467ecf976c782eecd4dc99644802cc60e2 < 313bbd1990b6ddfdaa7da098d0c56b098a833572 | 313bbd1990b6ddfdaa7da098d0c56b098a833572 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 5.10.84-1 | 5.10.84-1 |
| linux | linux_kernel | >= 0 < 5.14.12-1 | 5.14.12-1 |
| linux | linux_kernel | >= 0 < 5.14.12-1 | 5.14.12-1 |
| linux | linux_kernel | >= 0 < 5.14.12-1 | 5.14.12-1 |
| linux | linux_kernel | >= 3.9 < 5.4.151 | 5.4.151 |
| linux | linux_kernel | >= 5.11 < 5.14.10 | 5.14.10 |
| linux | linux_kernel | >= 5.5 < 5.10.71 | 5.10.71 |
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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OSV
CVE-2021-47396: In the Linux kernel, the following vulnerability has been resolved: mac80211-hwsim: fix late beacon hrtimer handling Thomas explained in https://lore
osv·2024-05-21·CVSS 5.5
CVE-2021-47396 [MEDIUM] CVE-2021-47396: In the Linux kernel, the following vulnerability has been resolved: mac80211-hwsim: fix late beacon hrtimer handling Thomas explained in https://lore
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
GHSA
GHSA-cwq4-fr9x-6844: In the Linux kernel, the following vulnerability has been resolved:
mac80211-hwsim: fix late beacon hrtimer handling
Thomas explained in https://lor
ghsa_unreviewed·2024-05-21
CVE-2021-47396 [MEDIUM] GHSA-cwq4-fr9x-6844: In the Linux kernel, the following vulnerability has been resolved:
mac80211-hwsim: fix late beacon hrtimer handling
Thomas explained in https://lor
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 wron
Red Hat
kernel: mac80211-hwsim: fix late beacon hrtimer handling
vendor_redhat·2024-05-21·CVSS 5.5
CVE-2021-47396 [MEDIUM] CWE-20 kernel: mac80211-hwsim: fix late beacon hrtimer handling
kernel: mac80211-hwsim: fix late beacon hrtimer handling
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
Debian
CVE-2021-47396: linux - In the Linux kernel, the following vulnerability has been resolved: mac80211-hw...
vendor_debian·2021·CVSS 5.5
CVE-2021-47396 [MEDIUM] CVE-2021-47396: linux - In the Linux kernel, the following vulnerability has been resolved: mac80211-hw...
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
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/2c204cf594df3b9468368dc9d0b24d482d93cda7https://git.kernel.org/stable/c/313bbd1990b6ddfdaa7da098d0c56b098a833572https://git.kernel.org/stable/c/9bee85de2c8155388c09a2e1530a243ec1c96f05https://git.kernel.org/stable/c/ed2adf69e29848d1eb9df99633dde655421c92edhttps://git.kernel.org/stable/c/2c204cf594df3b9468368dc9d0b24d482d93cda7https://git.kernel.org/stable/c/313bbd1990b6ddfdaa7da098d0c56b098a833572https://git.kernel.org/stable/c/9bee85de2c8155388c09a2e1530a243ec1c96f05https://git.kernel.org/stable/c/ed2adf69e29848d1eb9df99633dde655421c92ed
2024-05-21
Published