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).
Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 5.15.0-37.39 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 5.15.0-1011.14 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.4 | — | 5.4.0-1078.84~18.04.1 |
| linux-aws-5.8 | — | — |
| linux-aws-6.2 | — | — |
| linux-aws-fips | — | — |
| linux-azure | — | 5.15.0-1010.12 |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.15 | — | 5.15.0-1008.9~20.04.1 |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.4 | — | 5.4.0-1083.87~18.04.1 |
| linux-azure-5.8 | — | — |
| linux-azure-6.2 | — | — |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fips | — | — |
| linux-bluefield | — | — |
| linux-fips | — | — |
| linux-gcp | — | 5.15.0-1008.12 |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.4 | — | 5.4.0-1078.84~18.04.1 |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.2 | — | — |
| linux-gcp-fips | — | — |
| linux-gke | — | 5.15.0-1008.10 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 5.4.0-1046.48 |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.15 | — | 5.15.0-41.44~20.04.1 |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.4 | — | 5.4.0-117.132~18.04.1 |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-edge | — | — |
| linux-ibm | — | 5.15.0-1007.8 |
| linux-ibm-5.4 | — | 5.4.0-1028.32~18.04.1 |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | — |
| linux-intel-iotg | — | 5.15.0-1008.11 |
| linux-intel-iotg-5.15 | — | 5.15.0-1008.11~20.04.1 |
| linux-iot | — | 5.4.0-1004.6 |
| linux-kvm | — | 5.15.0-1010.11 |
| linux-lowlatency | — | 5.15.0-37.39 |
| linux-lowlatency-hwe-5.15 | — | 5.15.0-42.45~20.04.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-nvidia | — | — |
| linux-nvidia-6.2 | — | — |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | — |
| linux-oracle | — | 5.15.0-1009.12 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.4 | — | 5.4.0-1076.83~18.04.1 |
| linux-oracle-5.8 | — | — |
| linux-raspi | — | 5.15.0-1011.13 |
| linux-raspi-5.4 | — | 5.4.0-1065.75~18.04.1 |
| linux-raspi-realtime | — | — |
| linux-raspi2 | — | — |
| linux-realtime | — | 5.15.0-1014.14 |
| linux-riscv | — | — |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
References
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