Vulnerability Details : CVE-2021-46980
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.
Products affected by CVE-2021-46980
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-46980
0.04%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 5 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-46980
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
7.1
|
HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
1.8
|
5.2
|
NIST | 2024-12-31 |
CWE ids for CVE-2021-46980
-
The product reads data past the end, or before the beginning, of the intended buffer.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-46980
-
https://git.kernel.org/stable/c/1f4642b72be79757f050924a9b9673b6a02034bc
usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 - kernel/git/stable/linux.git - Linux kernel stable treePatch
-
https://git.kernel.org/stable/c/e5366bea0277425e1868ba20eeb27c879d5a6e2d
usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 - kernel/git/stable/linux.git - Linux kernel stable treePatch
-
https://git.kernel.org/stable/c/a453bfd7ef15fd9d524004d3ca7b05353a302911
usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 - kernel/git/stable/linux.git - Linux kernel stable treePatch
-
https://git.kernel.org/stable/c/5e9c6f58b01e6fdfbc740390c01f542a35c97e57
usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 - kernel/git/stable/linux.git - Linux kernel stable treePatch
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