CVE-2022-48821: misc: fastrpc: avoid double fput() on failed usercopy

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-16 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: avoid double fput() on failed usercopy If the copy back to userland fails for the FASTRPC_IOCTL_ALLOC_DMA_BUFF ioctl(), we shouldn't assume that 'buf->dmabuf' is still valid. In fact, dma_buf_fd() called fd_install() before, i.e. "consumed" one reference, leaving us with none. Calling dma_buf_put() will therefore put a reference we no longer own, leading to a valid file descritor table entry for an already released 'file' object which is a straight use-after-free. Simply avoid calling dma_buf_put() and rely on the process exit code to do the necessary cleanup, if needed, i.e. if the file descriptor is still valid.

Affected products

Linux kernel: from 5.1 before 5.4.180; from 5.5 before 5.10.101; from 5.11 before 5.15.24; from 5.16 before 5.16.10; 5.17-rc1, 5.17-rc2, 5.17-rc3 — fixed in 5.10.101, 5.15.24, 5.16.10, 5.4.180

How to fix

Upgrade to a fixed version: Linux kernel 5.10.101, 5.15.24, 5.16.10, 5.4.180. Check the vendor advisory for mitigations.

References

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