Ubuntu: (CVE-2021-46935): linux vulnerability

Ubuntu: (CVE-2021-46935): linux vulnerability

Severity

5

CVSS

(AV:L/AC:L/Au:S/C:C/I:N/A:N)

Published

02/27/2024

Created

11/21/2024

Added

11/19/2024

Modified

02/11/2025

Description

In the Linux kernel, the following vulnerability has been resolved: binder: fix async_free_space accounting for empty parcels In 4.13, commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") fixed a kernel structure visibility issue. As part of that patch, sizeof(void *) was used as the buffer size for 0-length data payloads so the driver could detect abusive clients sending 0-length asynchronous transactions to a server by enforcing limits on async_free_size. Unfortunately, on the "free" side, the accounting of async_free_space did not add the sizeof(void *) back. The result was that up to 8-bytes of async_free_space were leaked on every async transaction of 8-bytes or less.These small transactions are uncommon, so this accounting issue has gone undetected for several years. The fix is to use "buffer_size" (the allocated buffer size) instead of "size" (the logical buffer size) when updating the async_free_space during the free operation. These are the same except for this corner case of asynchronous transactions with payloads < 8 bytes.

Solution(s)

• ubuntu-upgrade-linux
• ubuntu-upgrade-linux-aws
• ubuntu-upgrade-linux-aws-5-4
• ubuntu-upgrade-linux-aws-fips
• ubuntu-upgrade-linux-aws-hwe
• ubuntu-upgrade-linux-azure
• ubuntu-upgrade-linux-azure-4-15
• ubuntu-upgrade-linux-azure-5-4
• ubuntu-upgrade-linux-azure-fips
• ubuntu-upgrade-linux-bluefield
• ubuntu-upgrade-linux-fips
• ubuntu-upgrade-linux-gcp
• ubuntu-upgrade-linux-gcp-4-15
• ubuntu-upgrade-linux-gcp-5-4
• ubuntu-upgrade-linux-gcp-fips
• ubuntu-upgrade-linux-gkeop
• ubuntu-upgrade-linux-hwe
• ubuntu-upgrade-linux-hwe-5-4
• ubuntu-upgrade-linux-ibm
• ubuntu-upgrade-linux-ibm-5-4
• ubuntu-upgrade-linux-kvm
• ubuntu-upgrade-linux-oracle
• ubuntu-upgrade-linux-oracle-5-4
• ubuntu-upgrade-linux-raspi
• ubuntu-upgrade-linux-raspi-5-4

References

• https://attackerkb.com/topics/cve-2021-46935
• CVE - 2021-46935
• https://git.kernel.org/linus/cfd0d84ba28c18b531648c9d4a35ecca89ad9901
• https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5da
• https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff
• https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4
• https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495
• https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593
• https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901
• https://www.cve.org/CVERecord?id=CVE-2021-46935

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