From: Dave Hansen <dave.hansen@intel.com>
To: Jiashuo Liang <liangjs@pku.edu.cn>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] x86/fault: Fix wrong signal when vsyscall fails with pkey
Date: Mon, 23 Aug 2021 07:55:33 -0700 [thread overview]
Message-ID: <d8105e66-8e67-889a-5762-47506e0cb393@intel.com> (raw)
In-Reply-To: <20210730030152.249106-1-liangjs@pku.edu.cn>
On 7/29/21 8:01 PM, Jiashuo Liang wrote:
> The function __bad_area_nosemaphore() calls kernelmode_fixup_or_oops() with
> parameter "signal" being "pkey", which will send a signal numbered "pkey".
>
> This bug appears when the kernel fail to access user-given memory pages
> that are protected by pkey, so it can go through the do_user_addr_fault()
> path and pass the !user_mode() check in __bad_area_nosemaphore(). Most
> cases will simply run the kernel fixup code to make an -EFAULT. But when
> another condition current->thread.sig_on_uaccess_err is met, which is
> only used to emulate vsyscall, we will generate the wrong signal.
>
> A new parameter "pkey" is added to kernelmode_fixup_or_oops() to fix it.
>
> Fixes: 5042d40a264c ("x86/fault: Bypass no_context() for implicit kernel faults from usermode")
> Signed-off-by: Jiashuo Liang <liangjs@pku.edu.cn>
This is pretty obscure, only affecting vsyscall emulation, but:
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
next prev parent reply other threads:[~2021-08-23 14:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 3:01 Jiashuo Liang
2021-08-23 14:55 ` Dave Hansen [this message]
2021-09-19 4:39 ` Jiashuo Liang
2021-09-20 10:42 ` [tip: x86/urgent] " tip-bot2 for Jiashuo Liang
2021-09-20 14:43 ` Borislav Petkov
2021-09-20 20:37 ` tip-bot2 for Jiashuo Liang
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