CVE-2024-36016: tty: n_gsm: fix possible out-of-bounds in gsm0_receive()

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-29 · updated 2026-08-04
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: tty: n_gsm: fix possible out-of-bounds in gsm0_receive() Assuming the following: - side A configures the n_gsm in basic option mode - side B sends the header of a basic option mode frame with data length 1 - side A switches to advanced option mode - side B sends 2 data bytes which exceeds gsm->len Reason: gsm->len is not used in advanced option mode. - side A switches to basic option mode - side B keeps sending until gsm0_receive() writes past gsm->buf Reason: Neither gsm->state nor gsm->len have been reset after reconfiguration. Fix this by changing gsm->count to gsm->len comparison from equal to less than. Also add upper limit checks against the constant MAX_MRU in gsm0_receive() and gsm1_receive() to harden against memory corruption of gsm->len and gsm->mru. All other checks remain as we still need to limit the data according to the user configuration and actual payload size.

Affected products

Linux kernel: from 2.6.35 before 4.19.316; from 4.20 before 5.4.278; from 5.5 before 5.10.219; from 5.11 before 5.15.161; from 5.16 before 6.1.93; from 6.2 before 6.6.33 — fixed in 4.19.316, 5.10.219, 5.15.161, 5.4.278, 6.1.93, 6.6.33

How to fix

Upgrade to a fixed version: Linux kernel 4.19.316, 5.10.219, 5.15.161, 5.4.278. Check the vendor advisory for mitigations.

References

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