| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-48629: crypto: qcom-rng - ensure buffer for generate is completely filled |
| |
| 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). |
| |
| The Linux kernel CVE team has assigned CVE-2022-48629 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 4.19.236 with commit a8e32bbb96c25b7ab29b1894dcd45e0b3b08fd9d |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 5.4.187 with commit 184f7bd08ce56f003530fc19f160d54e75bf5c9d |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 5.10.108 with commit 0f9b7b8df17525e464294c916acc8194ce38446b |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 5.15.31 with commit ab9337c7cb6f875b6286440b1adfbeeef2b2b2bd |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 5.16.17 with commit 485995cbc98a4f77cfd4f8ed4dd7ff8ab262964d |
| Issue introduced in 4.19 with commit ceec5f5b59882b871a722ca4d49b767a09a4bde9 and fixed in 5.17 with commit a680b1832ced3b5fa7c93484248fd221ea0d614b |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2022-48629 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/crypto/qcom-rng.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/a8e32bbb96c25b7ab29b1894dcd45e0b3b08fd9d |
| https://git.kernel.org/stable/c/184f7bd08ce56f003530fc19f160d54e75bf5c9d |
| https://git.kernel.org/stable/c/0f9b7b8df17525e464294c916acc8194ce38446b |
| https://git.kernel.org/stable/c/ab9337c7cb6f875b6286440b1adfbeeef2b2b2bd |
| https://git.kernel.org/stable/c/485995cbc98a4f77cfd4f8ed4dd7ff8ab262964d |
| https://git.kernel.org/stable/c/a680b1832ced3b5fa7c93484248fd221ea0d614b |
