# CVE-2021-46980: linux: In the Linux kernel, the following vulnerability has been resolved:  usb: typec: ucsi: Retrieve all the PDOs instead...

CVE-2021-46980 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-46980, released February 28, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-46980
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 28, 2024

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.38-1 | [DEBIAN-CVE-2021-46980](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46980.md) | Feb 28, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.38-1 | [DEBIAN-CVE-2021-46980](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46980.md) | Feb 28, 2024 |
| Linux | linux Debian 14 | 5.10.38-1 | [DEBIAN-CVE-2021-46980](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46980.md) | Feb 28, 2024 |

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