From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: mingo@kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH] x86/asm/memcpy_mcsafe: Fix copy_to_user_mcsafe() exception handling
Date: Tue, 3 Jul 2018 10:47:54 -0600 [thread overview]
Message-ID: <20180703164754.GB30451@linux.intel.com> (raw)
In-Reply-To: <153056565378.3420.295180898468362039.stgit@dwillia2-desk3.amr.corp.intel.com>
On Mon, Jul 02, 2018 at 02:16:10PM -0700, Dan Williams wrote:
> All copy_to_user() implementations need to be prepared to handle faults
> accessing userspace. The __memcpy_mcsafe() implementation handles both
> mmu-faults on the user destination and machine-check-exceptions on the
> source buffer. However, the memcpy_mcsafe() wrapper may silently
> fallback to memcpy() depending on build options and cpu-capabilities.
>
> Force copy_to_user_mcsafe() to always use __memcpy_mcsafe() when
> available, and otherwise disable all of the copy_to_user_mcsafe()
> infrastructure when __memcpy_mcsafe() is not available, i.e.
> CONFIG_X86_MCE=n.
>
> This fixes crashes of the form:
> run fstests generic/323 at 2018-07-02 12:46:23
> BUG: unable to handle kernel paging request at 00007f0d50001000
> RIP: 0010:__memcpy+0x12/0x20
> [..]
> Call Trace:
> copyout_mcsafe+0x3a/0x50
> _copy_to_iter_mcsafe+0xa1/0x4a0
> ? dax_alive+0x30/0x50
> dax_iomap_actor+0x1f9/0x280
> ? dax_iomap_rw+0x100/0x100
> iomap_apply+0xba/0x130
> ? dax_iomap_rw+0x100/0x100
> dax_iomap_rw+0x95/0x100
> ? dax_iomap_rw+0x100/0x100
> xfs_file_dax_read+0x7b/0x1d0 [xfs]
> xfs_file_read_iter+0xa7/0xc0 [xfs]
> aio_read+0x11c/0x1a0
>
> Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Tony Luck <tony.luck@intel.com>
> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
next prev parent reply other threads:[~2018-07-03 16:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-01 15:52 [PATCH] lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe Dan Williams
2018-07-02 16:58 ` Ross Zwisler
2018-07-02 17:17 ` Dan Williams
2018-07-02 21:16 ` [PATCH] x86/asm/memcpy_mcsafe: Fix copy_to_user_mcsafe() exception handling Dan Williams
2018-07-03 8:30 ` Ingo Molnar
2018-07-04 22:38 ` Al Viro
2018-07-04 23:02 ` Dan Williams
2018-07-05 7:02 ` Ingo Molnar
2018-07-03 16:47 ` Ross Zwisler [this message]
2018-07-03 16:47 ` [PATCH] lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe Ross Zwisler
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