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From:   Kees Cook <keescook@chromium.org>
To:     linux-kernel@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        clang-built-linux@googlegroups.com,
        Jarmo Tiitto <jarmo.tiitto@gmail.com>,
        Bill Wendling <wcw@google.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>
Cc:     Kees Cook <keescook@chromium.org>, morbo@google.com
Subject: Re: [PATCH v3 1/1] pgo: Fix sleep in atomic section in prf_open() v3
Date:   Mon,  7 Jun 2021 16:02:51 -0700
Message-Id: <162310696843.3797458.16031727600580374864.b4-ty@chromium.org>
In-Reply-To: <20210605183128.129614-1-jarmo.tiitto@gmail.com>
References: <20210605183128.129614-1-jarmo.tiitto@gmail.com>
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On Sat, 5 Jun 2021 21:31:29 +0300, Jarmo Tiitto wrote:
> In prf_open() the required buffer size can be so large that
> vzalloc() may sleep thus triggering bug:
> 
> ======
>  BUG: sleeping function called from invalid context at include/linux/sched/mm.h:201
>  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 337, name: cat
>  CPU: 1 PID: 337 Comm: cat Not tainted 5.13.0-rc2-24-hack+ #154
>  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>  Call Trace:
>   dump_stack+0xc7/0x134
>   ___might_sleep+0x177/0x190
>   __might_sleep+0x5a/0x90
>   kmem_cache_alloc_node_trace+0x6b/0x3a0
>   ? __get_vm_area_node+0xcd/0x1b0
>   ? dput+0x283/0x300
>   __get_vm_area_node+0xcd/0x1b0
>   __vmalloc_node_range+0x7b/0x420
>   ? prf_open+0x1da/0x580
>   ? prf_open+0x32/0x580
>   ? __llvm_profile_instrument_memop+0x36/0x50
>   vzalloc+0x54/0x60
>   ? prf_open+0x1da/0x580
>   prf_open+0x1da/0x580
>   full_proxy_open+0x211/0x370
>   ....
> ======
> 
> [...]

Applied to for-next/clang/features, thanks! I made some additional tweaks
on top of this, in a separate patch I just sent out.

[1/1] pgo: Fix sleep in atomic section in prf_open() v3
      https://git.kernel.org/kees/c/d13b0485a7bb

-- 
Kees Cook