mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-01-16 01:54:00 +00:00
12d908116f
Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is only called on exit, but __io_uring_free (which frees the tctx in which the registered ring pointers are stored) is also called on execve (via begin_new_exec -> io_uring_task_cancel -> __io_uring_cancel -> io_uring_cancel_generic -> __io_uring_free). This means: A process going through execve while having registered rings will leak references to the rings' `struct file`. Fix it by zapping registered rings on execve(). This is implemented by moving the io_uring_unreg_ringfd() from io_uring_files_cancel() into its callee __io_uring_cancel(), which is called from io_uring_task_cancel() on execve. This could probably be exploited *on 32-bit kernels* by leaking 2^32 references to the same ring, because the file refcount is stored in a pointer-sized field and get_file() doesn't have protection against refcount overflow, just a WARN_ONCE(); but on 64-bit it should have no impact beyond a memory leak. Cc: stable@vger.kernel.org Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors") Signed-off-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20241218-uring-reg-ring-cleanup-v1-1-8f63e999045b@google.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.