From: Borislav Petkov <bp@alien8.de>
To: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Andy Lutomirski" <luto@kernel.org>,
"Aili Yao" <yaoaili@kingsoft.com>,
"HORIGUCHI NAOYA( 堀口 直也)" <naoya.horiguchi@nec.com>
Subject: Re: [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison
Date: Wed, 7 Apr 2021 23:18:16 +0200 [thread overview]
Message-ID: <20210407211816.GP25319@zn.tnic> (raw)
In-Reply-To: <20210326000235.370514-4-tony.luck@intel.com>
On Thu, Mar 25, 2021 at 05:02:34PM -0700, Tony Luck wrote:
> Andy Lutomirski pointed out that sending SIGBUS to tasks that
> hit poison in the kernel copying syscall parameters from user
> address space is not the right semantic.
What does that mean exactly?
From looking at the code, that is this conditional:
if (t == EX_HANDLER_UACCESS && regs && is_copy_from_user(regs)) {
m->kflags |= MCE_IN_KERNEL_RECOV;
m->kflags |= MCE_IN_KERNEL_COPYIN;
so what does the above have to do with syscall params?
If it is about us being in ring 0 and touching user memory and eating
poison in same *user* memory while doing so, then sure, that makes
sense.
> So stop doing that. Add a new kill_me_never() call back that
> simply unmaps and offlines the poison page.
Right, that's the same as handling poisoned user memory.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-04-07 21:18 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 0:02 [RFC 0/4] Fix machine check recovery for copy_from_user Tony Luck
2021-03-26 0:02 ` [PATCH 1/4] x86/mce: Fix copyin code to return -EFAULT on machine check Tony Luck
2021-04-06 19:24 ` Borislav Petkov
2021-03-26 0:02 ` [PATCH 2/4] mce/iter: Check for copyin failure & return error up stack Tony Luck
2021-03-26 0:02 ` [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison Tony Luck
2021-04-07 21:18 ` Borislav Petkov [this message]
2021-04-07 21:43 ` Luck, Tony
2021-04-08 8:49 ` Borislav Petkov
2021-04-08 17:08 ` Luck, Tony
2021-04-13 10:07 ` Borislav Petkov
2021-04-13 16:13 ` Luck, Tony
2021-04-14 13:05 ` Borislav Petkov
2021-03-26 0:02 ` [PATCH 4/4] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-04-08 13:36 ` Borislav Petkov
2021-04-08 16:06 ` Luck, Tony
2021-04-08 2:13 ` [RFC 0/4] Fix machine check recovery for copy_from_user Aili Yao
2021-04-08 14:39 ` Luck, Tony
2021-04-09 6:49 ` Aili Yao
2021-04-14 5:47 [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison Jue Wang
2021-04-14 13:10 ` Borislav Petkov
2021-04-14 14:46 ` Jue Wang
2021-04-14 15:35 ` Borislav Petkov
2021-04-19 20:32 Jue Wang
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=20210407211816.GP25319@zn.tnic \
--to=bp@alien8.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=naoya.horiguchi@nec.com \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
--cc=yaoaili@kingsoft.com \
--subject='Re: [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison' \
/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).