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A pio send egress error can occur when the PSM library attempts to to send a bad packet. That issue is still being investigated. The pio error interrupt handler then attempts to progress the recovery of the errored pio send context. Code inspection reveals that the handling lacks the necessary locking if that recovery interleaves with a PSM close of the "context" object contains the pio send context. The lack of the locking can cause the recovery to access the already freed pio send context object and incorrectly deduce that the pio send context is actually a kernel pio send context as shown by the NULL deref stack below: [<ffffffff8143d78c>] _dev_info+0x6c/0x90 [<ffffffffc0613230>] sc_restart+0x70/0x1f0 [hfi1] [<ffffffff816ab124>] ? __schedule+0x424/0x9b0 [<ffffffffc06133c5>] sc_halted+0x15/0x20 [hfi1] [<ffffffff810aa3ba>] process_one_work+0x17a/0x440 [<ffffffff810ab086>] worker_thread+0x126/0x3c0 [<ffffffff810aaf60>] ? manage_workers.isra.24+0x2a0/0x2a0 [<ffffffff810b252f>] kthread+0xcf/0xe0 [<ffffffff810b2460>] ? insert_kthread_work+0x40/0x40 [<ffffffff816b8798>] ret_from_fork+0x58/0x90 [<ffffffff810b2460>] ? insert_kthread_work+0x40/0x40 This is the best case scenario and other scenarios can corrupt the already freed memory. Fix by adding the necessary locking in the pio send context error handler. Cc: <stable@vger.kernel.org> # 4.9.x Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.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.