CVE-2021-46935: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 4.14.0, before 4.14.261 (fixed in 4.14.261); from 4.15.0, before 4.19.224 (fixed in 4.19.224); from 4.20.0, before 5.4.170 (fixed in 5.4.170); from 5.5.0, before 5.10.90 (fixed in 5.10.90); from 5.11.0, before 5.15.13 (fixed in 5.15.13)

Published 2024-02-27. Last modified 2026-06-17.