If a user is accessing a file in selinuxfs with a pointer to a userspace buffer that is backed by e.g. a userfaultfd, the userspace access can stall indefinitely, which can block fsi->mutex if it is held. For sel_read_policy(), remove the locking, since this method doesn't seem to access anything that requires locking. For sel_read_bool(), move the user access below the locked region. For sel_write_bool() and sel_commit_bools_write(), move the user access up above the locked region. Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> [PM: removed an unused variable in sel_read_policy()] Signed-off-by: Paul Moore <paul@paul-moore.com>
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 Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.
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