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Caleb Sander Mateos
e663da62ba
5eff57fa9f("io_uring/uring_cmd: defer SQE copying until it's needed") moved the unconditional memcpy() of the uring_cmd SQE to async_data to 2 cases when the request goes async: - If REQ_F_FORCE_ASYNC is set to force the initial issue to go async - If ->uring_cmd() returns -EAGAIN in the initial non-blocking issue Unlike the REQ_F_FORCE_ASYNC case, in the EAGAIN case, io_uring_cmd() copies the SQE to async_data but neglects to update the io_uring_cmd's sqe field to point to async_data. As a result, sqe still points to the slot in the userspace-mapped SQ. At the end of io_submit_sqes(), the kernel advances the SQ head index, allowing userspace to reuse the slot for a new SQE. If userspace reuses the slot before the io_uring worker reissues the original SQE, the io_uring_cmd's SQE will be corrupted. Introduce a helper io_uring_cmd_cache_sqes() to copy the original SQE to the io_uring_cmd's async_data and point sqe there. Use it for both the REQ_F_FORCE_ASYNC and EAGAIN cases. This ensures the uring_cmd doesn't read from the SQ slot after it has been returned to userspace. Signed-off-by: Caleb Sander Mateos <csander@purestorage.com> Fixes:5eff57fa9f("io_uring/uring_cmd: defer SQE copying until it's needed") Link: https://lore.kernel.org/r/20250212204546.3751645-3-csander@purestorage.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.