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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Stefan Lippers-Hollmann <s.l-h@gmx.de>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>
Subject: Re: [PATCH 5.2 36/37] vhost: block speculation of translated descriptors
Date: Sat, 14 Sep 2019 09:08:36 +0100
Message-ID: <20190914080836.GB522114@kroah.com> (raw)
In-Reply-To: <20190914091548.230a63de@mir>

On Sat, Sep 14, 2019 at 09:15:48AM +0200, Stefan Lippers-Hollmann wrote:
> Hi
> 
> On 2019-09-14, Greg Kroah-Hartman wrote:
> > On Sat, Sep 14, 2019 at 02:54:11AM +0200, Stefan Lippers-Hollmann wrote:
> > > On 2019-09-13, Greg Kroah-Hartman wrote:
> > > > From: Michael S. Tsirkin <mst@redhat.com>
> > > >
> > > > commit a89db445fbd7f1f8457b03759aa7343fa530ef6b upstream.
> > > >
> > > > iovec addresses coming from vhost are assumed to be
> > > > pre-validated, but in fact can be speculated to a value
> > > > out of range.
> > > >
> > > > Userspace address are later validated with array_index_nospec so we can
> > > > be sure kernel info does not leak through these addresses, but vhost
> > > > must also not leak userspace info outside the allowed memory table to
> > > > guests.
> > > >
> > > > Following the defence in depth principle, make sure
> > > > the address is not validated out of node range.
> [...]
> > Do you have the same problem with Linus's tree right now?
> 
> Actually, yes I do (I had not tested i386 for 5.3~ within the last ~2
> weeks, only amd64). Very similar kernel config, same compiler versions
> but built in a slightly different environment (built directly on the bare
> iron, in a amd64 multilib userspace, rather than a pure-i386 chroot on an
> amd64 kernel).
> 
> $ git describe
> v5.3-rc8-36-ga7f89616b737
> 
> $ LANG= make ARCH=x86 -j1 bzImage modules
>   CALL    scripts/checksyscalls.sh
>   CALL    scripts/atomic/check-atomics.sh
>   CHK     include/generated/compile.h
>   CHK     kernel/kheaders_data.tar.xz
>   CC [M]  drivers/vhost/vhost.o
> In file included from ./include/linux/export.h:45,
>                  from ./include/linux/linkage.h:7,
>                  from ./include/linux/kernel.h:8,
>                  from ./include/linux/list.h:9,
>                  from ./include/linux/wait.h:7,
>                  from ./include/linux/eventfd.h:13,
>                  from drivers/vhost/vhost.c:13:
> drivers/vhost/vhost.c: In function 'translate_desc':
> ./include/linux/compiler.h:350:38: error: call to '__compiletime_assert_2076' declared with attribute error: BUILD_BUG_ON failed: sizeof(_s) > sizeof(long)
>   350 |  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
>       |                                      ^
> ./include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert'
>   331 |    prefix ## suffix();    \
>       |    ^~~~~~
> ./include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert'
>   350 |  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
>       |  ^~~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
>    39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>       |                                     ^~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
>    50 |  BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
>       |  ^~~~~~~~~~~~~~~~
> ./include/linux/nospec.h:56:2: note: in expansion of macro 'BUILD_BUG_ON'
>    56 |  BUILD_BUG_ON(sizeof(_s) > sizeof(long));   \
>       |  ^~~~~~~~~~~~
> drivers/vhost/vhost.c:2076:5: note: in expansion of macro 'array_index_nospec'
>  2076 |     array_index_nospec((unsigned long)(addr - node->start),
>       |     ^~~~~~~~~~~~~~~~~~
> make[2]: *** [scripts/Makefile.build:281: drivers/vhost/vhost.o] Error 1
> make[1]: *** [scripts/Makefile.build:497: drivers/vhost] Error 2
> make: *** [Makefile:1083: drivers] Error 2
> 
> $ git revert a89db445fbd7f1f8457b03759aa7343fa530ef6b
> 
> $ LANG= make ARCH=x86 -j16 bzImage modules
>   CALL    scripts/atomic/check-atomics.sh
>   CALL    scripts/checksyscalls.sh
>   CHK     include/generated/compile.h
>   CHK     kernel/kheaders_data.tar.xz
>   Building modules, stage 2.
> Kernel: arch/x86/boot/bzImage is ready  (#1)
>   MODPOST 3464 modules
> 
> $ echo $?
> 0
> 
> $ find . -name vhost\\.ko
> ./drivers/vhost/vhost.ko
> 
> I've attached the affected kernel config for v5.3~/ i386.

Ok, good, we will be "bug compatible" at the very least now :)

When this gets fixed in Linus's tree we can backport the fix here as
well.  The number of users of that compiler version/configuration is
probably pretty low at the moment to want to hold off on this fix.

thanks,

greg k-h

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 13:07 [PATCH 5.2 00/37] 5.2.15-stable review Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 01/37] gpio: pca953x: correct type of reg_direction Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 02/37] gpio: pca953x: use pca953x_read_regs instead of regmap_bulk_read Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 03/37] ALSA: hda - Fix potential endless loop at applying quirks Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 04/37] ALSA: hda/realtek - Fix overridden device-specific initialization Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 05/37] ALSA: hda/realtek - Add quirk for HP Pavilion 15 Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 06/37] ALSA: hda/realtek - Enable internal speaker & headset mic of ASUS UX431FL Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 07/37] ALSA: hda/realtek - Fix the problem of two front mics on a ThinkCentre Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 08/37] sched/fair: Dont assign runtime for throttled cfs_rq Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 09/37] drm/vmwgfx: Fix double free in vmw_recv_msg() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 10/37] drm/nouveau/sec2/gp102: add missing MODULE_FIRMWAREs Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 11/37] vhost/test: fix build for vhost test Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 12/37] vhost/test: fix build for vhost test - again Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 13/37] powerpc/64e: Drop stale call to smp_processor_id() which hangs SMP startup Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 14/37] powerpc/tm: Fix FP/VMX unavailable exceptions inside a transaction Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 15/37] powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 16/37] batman-adv: fix uninit-value in batadv_netlink_get_ifindex() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 17/37] batman-adv: Only read OGM tvlv_len after buffer len check Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 18/37] bcache: only clear BTREE_NODE_dirty bit when it is set Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 19/37] bcache: add comments for mutex_lock(&b->write_lock) Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 20/37] bcache: fix race in btree_flush_write() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 21/37] IB/rdmavt: Add new completion inline Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 22/37] IB/{rdmavt, qib, hfi1}: Convert to new completion API Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 23/37] IB/hfi1: Unreserve a flushed OPFN request Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 24/37] drm/i915: Disable SAMPLER_STATE prefetching on all Gen11 steppings Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 25/37] drm/i915: Make sure cdclk is high enough for DP audio on VLV/CHV Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 26/37] mmc: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 27/37] usb: chipidea: imx: add imx7ulp support Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 28/37] usb: chipidea: imx: fix EPROBE_DEFER support during driver probe Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 29/37] virtio/s390: fix race on airq_areas[] Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 30/37] drm/i915: Support flags in whitlist WAs Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 31/37] drm/i915: Support whitelist workarounds on all engines Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 32/37] drm/i915: whitelist PS_(DEPTH|INVOCATION)_COUNT Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 33/37] drm/i915: Add whitelist workarounds for ICL Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 34/37] drm/i915/icl: whitelist PS_(DEPTH|INVOCATION)_COUNT Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 35/37] Btrfs: fix unwritten extent buffers and hangs on future writeback attempts Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 36/37] vhost: block speculation of translated descriptors Greg Kroah-Hartman
2019-09-14  0:54   ` Stefan Lippers-Hollmann
2019-09-14  5:50     ` Greg Kroah-Hartman
2019-09-14  7:15       ` Stefan Lippers-Hollmann
2019-09-14  8:08         ` Greg Kroah-Hartman [this message]
2019-09-15  9:34           ` Thomas Backlund
2019-09-15 13:37             ` Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 5.2 37/37] vhost: make sure log_num < in_num Greg Kroah-Hartman
2019-09-13 19:39 ` [PATCH 5.2 00/37] 5.2.15-stable review kernelci.org bot
2019-09-14  4:26 ` Naresh Kamboju
2019-09-14  7:43   ` Greg Kroah-Hartman
2019-09-14 14:08 ` Guenter Roeck
2019-09-15 13:34 ` Greg Kroah-Hartman
2019-09-16  9:25 ` Jon Hunter
2019-09-16 10:41   ` Greg Kroah-Hartman

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