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

2024-05-2918:46:34

Linux

github.com

linux kernel

vulnerability

n_gsm

out-of-bounds

data length

advanced option mode

memory corruption

AI Score

7.1

Confidence

High

EPSS

Percentile

13.0%

SSVC

Exploitation

none

Automatable

Technical Impact

partial

JSON

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.

ADP Affected

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    "vendor": "linux",
    "product": "linux_kernel",
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        "versionType": "custom"
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    "defaultStatus": "unknown"
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  {
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      "cpe:2.3:o:linux:linux_kernel:2.6.35:*:*:*:*:*:*:*"
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