CVE-2021-47305: dma-buf/sync_file: Don't leak fences on merge failure

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-21 · updated 2026-06-17
Weakness: CWE-617

Description

In the Linux kernel, the following vulnerability has been resolved: dma-buf/sync_file: Don't leak fences on merge failure Each add_fence() call does a dma_fence_get() on the relevant fence. In the error path, we weren't calling dma_fence_put() so all those fences got leaked. Also, in the krealloc_array failure case, we weren't freeing the fences array. Instead, ensure that i and fences are always zero-initialized and dma_fence_put() all the fences and kfree(fences) on every error path.

Affected products

Linux kernel: from 4.9 before 4.14.241; from 4.15 before 4.19.199; from 4.20 before 5.4.135; from 5.5 before 5.10.53; from 5.11 before 5.13.5; 5.14-rc1 — fixed in 4.14.241, 4.19.199, 5.10.53, 5.13.5, 5.4.135

How to fix

Upgrade to a fixed version: Linux kernel 4.14.241, 4.19.199, 5.10.53, 5.13.5. Check the vendor advisory for mitigations.

References

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