From: Kees Cook <keescook@chromium.org>
To: Alexander Lobakin <alobakin@pm.me>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Jinyang He <hejinyang@loongson.cn>,
Ralf Baechle <ralf@linux-mips.org>,
Matt Redfearn <matt.redfearn@mips.com>,
linux-mips@vger.kernel.org, stable@vger.kernel.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH mips-fixes] MIPS: relocatable: fix possible boot hangup with KASLR enabled
Date: Mon, 11 Jan 2021 11:52:31 -0800 [thread overview]
Message-ID: <202101111152.CBF4BEDB@keescook> (raw)
In-Reply-To: <20210110142023.185275-1-alobakin@pm.me>
On Sun, Jan 10, 2021 at 02:21:05PM +0000, Alexander Lobakin wrote:
> LLVM-built Linux triggered a boot hangup with KASLR enabled.
>
> arch/mips/kernel/relocate.c:get_random_boot() uses linux_banner,
> which is a string constant, as a random seed, but accesses it
> as an array of unsigned long (in rotate_xor()).
> When the address of linux_banner is not aligned to sizeof(long),
> such access emits unaligned access exception and hangs the kernel.
>
> Use PTR_ALIGN() to align input address to sizeof(long) and also
> align down the input length to prevent possible access-beyond-end.
>
> Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE")
> Cc: stable@vger.kernel.org # 4.7+
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2021-01-11 19:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-10 14:21 [PATCH mips-fixes] MIPS: relocatable: fix possible boot hangup with KASLR enabled Alexander Lobakin
2021-01-11 5:21 ` Nathan Chancellor
2021-01-11 19:52 ` Kees Cook [this message]
2021-01-13 10:43 ` Thomas Bogendoerfer
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