# CVE-2022-48629: linux: In the Linux kernel, the following vulnerability has been resolved:  crypto: qcom-rng - ensure buffer for generate is...

CVE-2022-48629 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-48629, released March 5, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-48629
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0054
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 5, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  crypto: qcom-rng - ensure buffer for generate is completely filled  The generate function in struct rng_alg expects that the destination buffer is completely filled if the function returns 0. qcom_rng_read() can run into a situation where the buffer is partially filled with randomness and the remaining part of the buffer is zeroed since qcom_rng_generate() doesn't check the return value. This issue can be reproduced by running the following from libkcapi:      kcapi-rng -b 9000000 > OUTFILE  The generated OUTFILE will have three huge sections that contain all zeros, and this is caused by the code where the test 'val & PRNG_STATUS_DATA_AVAIL' fails.  Let's fix this issue by ensuring that qcom_rng_read() always returns with a full buffer if the function returns success. Let's also have qcom_rng_generate() return the correct value.  Here's some statistics from the ent project (https://www.fourmilab.ch/random/) that shows information about the quality of the generated numbers:      $ ent -c qcom-random-before     Value Char Occurrences Fraction       0           606748   0.067416       1            33104   0.003678       2            33001   0.003667     ...     253   �        32883   0.003654     254   �        33035   0.003671     255   �        33239   0.003693      Total:       9000000   1.000000      Entropy = 7.811590 bits per byte.      Optimum compression would reduce the size     of this 9000000 byte file by 2 percent.      Chi square distribution for 9000000 samples is 9329962.81, and     randomly would exceed this value less than 0.01 percent of the     times.      Arithmetic mean value of data bytes is 119.3731 (127.5 = random).     Monte Carlo value for Pi is 3.197293333 (error 1.77 percent).     Serial correlation coefficient is 0.159130 (totally uncorrelated =     0.0).  Without this patch, the results of the chi-square test is 0.01%, and the numbers are certainly not random according to ent's project page. The results improve with this patch:      $ ent -c qcom-random-after     Value Char Occurrences Fraction       0            35432   0.003937       1            35127   0.003903       2            35424   0.003936     ...     253   �        35201   0.003911     254   �        34835   0.003871     255   �        35368   0.003930      Total:       9000000   1.000000      Entropy = 7.999979 bits per byte.      Optimum compression would reduce the size     of this 9000000 byte file by 0 percent.      Chi square distribution for 9000000 samples is 258.77, and randomly     would exceed this value 42.24 percent of the times.      Arithmetic mean value of data bytes is 127.5006 (127.5 = random).     Monte Carlo value for Pi is 3.141277333 (error 0.01 percent).     Serial correlation coefficient is 0.000468 (totally uncorrelated =     0.0).  This change was tested on a Nexus 5 phone (msm8974 SoC).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.16.18-1 | [DEBIAN-CVE-2022-48629](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48629.md) | Mar 5, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.16.18-1 | [DEBIAN-CVE-2022-48629](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48629.md) | Mar 5, 2024 |
| Linux | linux Debian 14 | 5.16.18-1 | [DEBIAN-CVE-2022-48629](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48629.md) | Mar 5, 2024 |

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