linux-kernel - Re: [PATCH v6 6/44] kmsan: add ReST documentation

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Date:   Tue, 6 Sep 2022 10:10:26 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v6 6/44] kmsan: add ReST documentation

On Mon, Sep 05, 2022 at 02:24:14PM +0200, Alexander Potapenko wrote:
> +Here is an example of a KMSAN report::
> +
> +  =====================================================
> +  BUG: KMSAN: uninit-value in test_uninit_kmsan_check_memory+0x1be/0x380 [kmsan_test]
> +   test_uninit_kmsan_check_memory+0x1be/0x380 mm/kmsan/kmsan_test.c:273
> +   kunit_run_case_internal lib/kunit/test.c:333
> +   kunit_try_run_case+0x206/0x420 lib/kunit/test.c:374
> +   kunit_generic_run_threadfn_adapter+0x6d/0xc0 lib/kunit/try-catch.c:28
> +   kthread+0x721/0x850 kernel/kthread.c:327
> +   ret_from_fork+0x1f/0x30 ??:?
> +
> +  Uninit was stored to memory at:
> +   do_uninit_local_array+0xfa/0x110 mm/kmsan/kmsan_test.c:260
> +   test_uninit_kmsan_check_memory+0x1a2/0x380 mm/kmsan/kmsan_test.c:271
> +   kunit_run_case_internal lib/kunit/test.c:333
> +   kunit_try_run_case+0x206/0x420 lib/kunit/test.c:374
> +   kunit_generic_run_threadfn_adapter+0x6d/0xc0 lib/kunit/try-catch.c:28
> +   kthread+0x721/0x850 kernel/kthread.c:327
> +   ret_from_fork+0x1f/0x30 ??:?
> +
> +  Local variable uninit created at:
> +   do_uninit_local_array+0x4a/0x110 mm/kmsan/kmsan_test.c:256
> +   test_uninit_kmsan_check_memory+0x1a2/0x380 mm/kmsan/kmsan_test.c:271
> +
> +  Bytes 4-7 of 8 are uninitialized
> +  Memory access of size 8 starts at ffff888083fe3da0
> +
> +  CPU: 0 PID: 6731 Comm: kunit_try_catch Tainted: G    B       E     5.16.0-rc3+ #104
> +  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
> +  =====================================================

Are these table markers in the code block above part of kmsan output?

> +A use of uninitialized value ``v`` is reported by KMSAN in the following cases:
> + - in a condition, e.g. ``if (v) { ... }``;
> + - in an indexing or pointer dereferencing, e.g. ``array[v]`` or ``*v``;
> + - when it is copied to userspace or hardware, e.g. ``copy_to_user(..., &v, ...)``;
> + - when it is passed as an argument to a function, and
> +   ``CONFIG_KMSAN_CHECK_PARAM_RETVAL`` is enabled (see below).

The sentence before the list above is rendered as definition list term
instead, so I add the blank line separator:

---- >8 ----

diff --git a/Documentation/dev-tools/kmsan.rst b/Documentation/dev-tools/kmsan.rst
index 2a53a801198cbf..55fa82212eb255 100644
--- a/Documentation/dev-tools/kmsan.rst
+++ b/Documentation/dev-tools/kmsan.rst
@@ -67,6 +67,7 @@ uninitialized in the local variable, as well as the stack where the value was
 copied to another memory location before use.
 
 A use of uninitialized value ``v`` is reported by KMSAN in the following cases:
+
  - in a condition, e.g. ``if (v) { ... }``;
  - in an indexing or pointer dereferencing, e.g. ``array[v]`` or ``*v``;
  - when it is copied to userspace or hardware, e.g. ``copy_to_user(..., &v, ...)``;

Thanks. 

-- 
An old man doll... just what I always wanted! - Clara

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