CVE-2021-47444: drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-22 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read In commit e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid corruption test") the function connector_bad_edid() started assuming that the memory for the EDID passed to it was big enough to hold `edid[0x7e] + 1` blocks of data (1 extra for the base block). It completely ignored the fact that the function was passed `num_blocks` which indicated how much memory had been allocated for the EDID. Let's fix this by adding a bounds check. This is important for handling the case where there's an error in the first block of the EDID. In that case we will call connector_bad_edid() without having re-allocated memory based on `edid[0x7e]`.

Affected products

Linux kernel: from 5.7 before 5.10.75; from 5.11 before 5.14.14; 5.15-rc1, 5.15-rc2, 5.15-rc3, 5.15-rc4, 5.15-rc5 — fixed in 5.10.75, 5.14.14

How to fix

Upgrade to a fixed version: Linux kernel 5.10.75, 5.14.14. Check the vendor advisory for mitigations.

References

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