d22cc7f67d
The following commit:7f26482a87("locking/percpu-rwsem: Remove the embedded rwsem") introduced task_struct memory leaks due to messing up the task_struct refcount. At the beginning of percpu_rwsem_wake_function(), it calls get_task_struct(), but if the trylock failed, it will remain in the waitqueue. However, it will run percpu_rwsem_wake_function() again with get_task_struct() to increase the refcount but then only call put_task_struct() once the trylock succeeded. Fix it by adjusting percpu_rwsem_wake_function() a bit to guard against when percpu_rwsem_wait() observing !private, terminating the wait and doing a quick exit() while percpu_rwsem_wake_function() then doing wake_up_process(p) as a use-after-free. Fixes:7f26482a87("locking/percpu-rwsem: Remove the embedded rwsem") Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200330213002.2374-1-cai@lca.pw
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.
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.