CVE-2026-90044usb: gadget: f_fs: Fix Use-After-Free in AIO error path

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/922a29e1f8573fd405eea1a73a52112c4e7fcfc4
• https://git.kernel.org/stable/c/0a2f71ccf9c2053de725e9a7922d081f3f3a3804
• https://git.kernel.org/stable/c/b5f0e80a03e87bd932487e03248eae3ba3ed7b45
• https://git.kernel.org/stable/c/153b5ecd29ed055562400bc17c91df3fd869b0ce
• https://git.kernel.org/stable/c/4a2fb2d12b87b43724230abb52a1440617c7b6cc
• https://git.kernel.org/stable/c/e78dcb1f7ec271449c54984dc90c62a5ba272de7