LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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>

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d8105e66-8e67-889a-5762-47506e0cb393@intel.com \
    --to=dave.hansen@intel.com \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=liangjs@pku.edu.cn \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v2] x86/fault: Fix wrong signal when vsyscall fails with pkey' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).