Bug 2535235 (CVE-2026-90044) - CVE-2026-90044 kernel: usb: gadget: f_fs: Fix Use-After-Free in AIO error path
Summary: CVE-2026-90044 kernel: usb: gadget: f_fs: Fix Use-After-Free in AIO error path
Keywords:
Status: NEW
Alias: CVE-2026-90044
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-16 11:38 UTC by OSIDB Bzimport
Modified: 2026-11-04 18:55 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-09-16 11:38:31 UTC
In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: f_fs: Fix Use-After-Free in AIO error path

In ffs_epfile_write_iter() and ffs_epfile_read_iter(), when ffs_epfile_io()
fails with an error other than -EIOCBQUEUED, the io_data structure (`p`) is
freed. However, for AIO operations, the kiocb cancel function was already
armed and kiocb->private was set to `p`.

If a concurrent cancel operation (such as sys_io_cancel()) executes after
ffs_epfile_io() fails but before the function frees `p`, a Use-After-Free
can occur when the cancellation handler accesses the freed pointer.

To securely fix this race condition, we must properly un-arm the
cancellation. Invoking `kiocb->ki_complete()` does exactly this by
acquiring `ctx->ctx_lock` and safely removing the kiocb from the active
sequence. In doing so, it ensures that a parallel io_cancel can no longer
discover the kiocb, effectively closing the race window.

We then return -EIOCBQUEUED to notify the VFS layer that the kiocb has been
consumed and it should avoid attempting to complete the request again or
triggering subsequent completion handlers.


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