CVE-2021-46980 Affecting kernel-preempt package, versions <5.3.18-150300.59.158.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES153-KERNELPREEMPT-7720904
- published20 Aug 2024
- disclosed3 May 2024
Introduced: 3 May 2024
CVE-2021-46980 (opens in a new tab)How to fix?
Upgrade SLES:15.3 kernel-preempt to version 5.3.18-150300.59.158.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-preempt package and not the kernel-preempt package as distributed by SLES.
See How to fix? for SLES:15.3 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4
commit 4dbc6a4ef06d ("usb: typec: ucsi: save power data objects in PD mode") introduced retrieval of the PDOs when connected to a PD-capable source. But only the first 4 PDOs are received since that is the maximum number that can be fetched at a time given the MESSAGE_IN length limitation (16 bytes). However, as per the PD spec a connected source may advertise up to a maximum of 7 PDOs.
If such a source is connected it's possible the PPM could have negotiated a power contract with one of the PDOs at index greater than 4, and would be reflected in the request data object's (RDO) object position field. This would result in an out-of-bounds access when the rdo_index() is used to index into the src_pdos array in ucsi_psy_get_voltage_now().
With the help of the UBSAN -fsanitize=array-bounds checker enabled this exact issue is revealed when connecting to a PD source adapter that advertise 5 PDOs and the PPM enters a contract having selected the 5th one.
[ 151.545106][ T70] Unexpected kernel BRK exception at EL1 [ 151.545112][ T70] Internal error: BRK handler: f2005512 [#1] PREEMPT SMP ... [ 151.545499][ T70] pc : ucsi_psy_get_prop+0x208/0x20c [ 151.545507][ T70] lr : power_supply_show_property+0xc0/0x328 ... [ 151.545542][ T70] Call trace: [ 151.545544][ T70] ucsi_psy_get_prop+0x208/0x20c [ 151.545546][ T70] power_supply_uevent+0x1a4/0x2f0 [ 151.545550][ T70] dev_uevent+0x200/0x384 [ 151.545555][ T70] kobject_uevent_env+0x1d4/0x7e8 [ 151.545557][ T70] power_supply_changed_work+0x174/0x31c [ 151.545562][ T70] process_one_work+0x244/0x6f0 [ 151.545564][ T70] worker_thread+0x3e0/0xa64
We can resolve this by instead retrieving and storing up to the maximum of 7 PDOs in the con->src_pdos array. This would involve two calls to the GET_PDOS command.
References
- https://www.suse.com/security/cve/CVE-2021-46980.html
- https://bugzilla.suse.com/1220663
- https://git.kernel.org/stable/c/1f4642b72be79757f050924a9b9673b6a02034bc
- https://git.kernel.org/stable/c/5e9c6f58b01e6fdfbc740390c01f542a35c97e57
- https://git.kernel.org/stable/c/a453bfd7ef15fd9d524004d3ca7b05353a302911
- https://git.kernel.org/stable/c/e5366bea0277425e1868ba20eeb27c879d5a6e2d