<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/linux, branch v4.19.196</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ptp: improve max_adj check against unreasonable values</title>
<updated>2021-06-30T12:48:19+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2021-06-14T22:24:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cee0a9c1826bebd7c2578ad0dcff06eb68868069'/>
<id>cee0a9c1826bebd7c2578ad0dcff06eb68868069</id>
<content type='text'>
[ Upstream commit 475b92f932168a78da8109acd10bfb7578b8f2bb ]

Scaled PPM conversion to PPB may (on 64bit systems) result
in a value larger than s32 can hold (freq/scaled_ppm is a long).
This means the kernel will not correctly reject unreasonably
high -&gt;freq values (e.g. &gt; 4294967295ppb, 281474976645 scaled PPM).

The conversion is equivalent to a division by ~66 (65.536),
so the value of ppb is always smaller than ppm, but not small
enough to assume narrowing the type from long -&gt; s32 is okay.

Note that reasonable user space (e.g. ptp4l) will not use such
high values, anyway, 4289046510ppb ~= 4.3x, so the fix is
somewhat pedantic.

Fixes: d39a743511cd ("ptp: validate the requested frequency adjustment.")
Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 475b92f932168a78da8109acd10bfb7578b8f2bb ]

Scaled PPM conversion to PPB may (on 64bit systems) result
in a value larger than s32 can hold (freq/scaled_ppm is a long).
This means the kernel will not correctly reject unreasonably
high -&gt;freq values (e.g. &gt; 4294967295ppb, 281474976645 scaled PPM).

The conversion is equivalent to a division by ~66 (65.536),
so the value of ppb is always smaller than ppm, but not small
enough to assume narrowing the type from long -&gt; s32 is okay.

Note that reasonable user space (e.g. ptp4l) will not use such
high values, anyway, 4289046510ppb ~= 4.3x, so the fix is
somewhat pedantic.

Fixes: d39a743511cd ("ptp: validate the requested frequency adjustment.")
Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: ptp_clock: Publish scaled_ppm_to_ppb</title>
<updated>2021-06-30T12:48:19+00:00</updated>
<author>
<name>Shalom Toledo</name>
<email>shalomt@mellanox.com</email>
</author>
<published>2019-06-11T15:45:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b5200624e643bb4cf65eb3b6d9bf36fc11982669'/>
<id>b5200624e643bb4cf65eb3b6d9bf36fc11982669</id>
<content type='text'>
[ Upstream commit 4368dada5b37e74a13b892ca5cef8a7d558e9a5f ]

Publish scaled_ppm_to_ppb to allow drivers to use it.

Signed-off-by: Shalom Toledo &lt;shalomt@mellanox.com&gt;
Reviewed-by: Petr Machata &lt;petrm@mellanox.com&gt;
Signed-off-by: Ido Schimmel &lt;idosch@mellanox.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 4368dada5b37e74a13b892ca5cef8a7d558e9a5f ]

Publish scaled_ppm_to_ppb to allow drivers to use it.

Signed-off-by: Shalom Toledo &lt;shalomt@mellanox.com&gt;
Reviewed-by: Petr Machata &lt;petrm@mellanox.com&gt;
Signed-off-by: Ido Schimmel &lt;idosch@mellanox.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: make get_net_ns return error if NET_NS is disabled</title>
<updated>2021-06-30T12:48:18+00:00</updated>
<author>
<name>Changbin Du</name>
<email>changbin.du@gmail.com</email>
</author>
<published>2021-06-11T14:29:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=29174c883e493b612170b7874e560e006d18985a'/>
<id>29174c883e493b612170b7874e560e006d18985a</id>
<content type='text'>
[ Upstream commit ea6932d70e223e02fea3ae20a4feff05d7c1ea9a ]

There is a panic in socket ioctl cmd SIOCGSKNS when NET_NS is not enabled.
The reason is that nsfs tries to access ns-&gt;ops but the proc_ns_operations
is not implemented in this case.

[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010
[7.670268] pgd = 32b54000
[7.670544] [00000010] *pgd=00000000
[7.671861] Internal error: Oops: 5 [#1] SMP ARM
[7.672315] Modules linked in:
[7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16
[7.673309] Hardware name: Generic DT based system
[7.673642] PC is at nsfs_evict+0x24/0x30
[7.674486] LR is at clear_inode+0x20/0x9c

The same to tun SIOCGSKNS command.

To fix this problem, we make get_net_ns() return -EINVAL when NET_NS is
disabled. Meanwhile move it to right place net/core/net_namespace.c.

Signed-off-by: Changbin Du &lt;changbin.du@gmail.com&gt;
Fixes: c62cce2caee5 ("net: add an ioctl to get a socket network namespace")
Cc: Cong Wang &lt;xiyou.wangcong@gmail.com&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: David Laight &lt;David.Laight@ACULAB.COM&gt;
Cc: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
Suggested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ea6932d70e223e02fea3ae20a4feff05d7c1ea9a ]

There is a panic in socket ioctl cmd SIOCGSKNS when NET_NS is not enabled.
The reason is that nsfs tries to access ns-&gt;ops but the proc_ns_operations
is not implemented in this case.

[7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010
[7.670268] pgd = 32b54000
[7.670544] [00000010] *pgd=00000000
[7.671861] Internal error: Oops: 5 [#1] SMP ARM
[7.672315] Modules linked in:
[7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16
[7.673309] Hardware name: Generic DT based system
[7.673642] PC is at nsfs_evict+0x24/0x30
[7.674486] LR is at clear_inode+0x20/0x9c

The same to tun SIOCGSKNS command.

To fix this problem, we make get_net_ns() return -EINVAL when NET_NS is
disabled. Meanwhile move it to right place net/core/net_namespace.c.

Signed-off-by: Changbin Du &lt;changbin.du@gmail.com&gt;
Fixes: c62cce2caee5 ("net: add an ioctl to get a socket network namespace")
Cc: Cong Wang &lt;xiyou.wangcong@gmail.com&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: David Laight &lt;David.Laight@ACULAB.COM&gt;
Cc: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
Suggested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: add documentation to socket.c</title>
<updated>2021-06-30T12:48:18+00:00</updated>
<author>
<name>Pedro Tammela</name>
<email>pctammela@gmail.com</email>
</author>
<published>2019-03-14T13:45:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=137e2b34d1c6304b1fa2d55d5232a457bf8b2655'/>
<id>137e2b34d1c6304b1fa2d55d5232a457bf8b2655</id>
<content type='text'>
[ Upstream commit 8a3c245c031944f2176118270e7bc5d4fd4a1075 ]

Adds missing sphinx documentation to the
socket.c's functions. Also fixes some whitespaces.

I also changed the style of older documentation as an
effort to have an uniform documentation style.

Signed-off-by: Pedro Tammela &lt;pctammela@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 8a3c245c031944f2176118270e7bc5d4fd4a1075 ]

Adds missing sphinx documentation to the
socket.c's functions. Also fixes some whitespaces.

I also changed the style of older documentation as an
effort to have an uniform documentation style.

Signed-off-by: Pedro Tammela &lt;pctammela@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>HID: usbhid: fix info leak in hid_submit_ctrl</title>
<updated>2021-06-30T12:48:10+00:00</updated>
<author>
<name>Anirudh Rayabharam</name>
<email>mail@anirudhrb.com</email>
</author>
<published>2021-04-25T17:33:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0e280502be1b003c3483ae03fc60dea554fcfa82'/>
<id>0e280502be1b003c3483ae03fc60dea554fcfa82</id>
<content type='text'>
[ Upstream commit 6be388f4a35d2ce5ef7dbf635a8964a5da7f799f ]

In hid_submit_ctrl(), the way of calculating the report length doesn't
take into account that report-&gt;size can be zero. When running the
syzkaller reproducer, a report of size 0 causes hid_submit_ctrl) to
calculate transfer_buffer_length as 16384. When this urb is passed to
the usb core layer, KMSAN reports an info leak of 16384 bytes.

To fix this, first modify hid_report_len() to account for the zero
report size case by using DIV_ROUND_UP for the division. Then, call it
from hid_submit_ctrl().

Reported-by: syzbot+7c2bb71996f95a82524c@syzkaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam &lt;mail@anirudhrb.com&gt;
Acked-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6be388f4a35d2ce5ef7dbf635a8964a5da7f799f ]

In hid_submit_ctrl(), the way of calculating the report length doesn't
take into account that report-&gt;size can be zero. When running the
syzkaller reproducer, a report of size 0 causes hid_submit_ctrl) to
calculate transfer_buffer_length as 16384. When this urb is passed to
the usb core layer, KMSAN reports an info leak of 16384 bytes.

To fix this, first modify hid_report_len() to account for the zero
report size case by using DIV_ROUND_UP for the division. Then, call it
from hid_submit_ctrl().

Reported-by: syzbot+7c2bb71996f95a82524c@syzkaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam &lt;mail@anirudhrb.com&gt;
Acked-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kvm: fix previous commit for 32-bit builds</title>
<updated>2021-06-16T09:55:01+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2021-06-09T05:49:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=270dadd7ea31c1bc43a0b1de118a30c2238171a8'/>
<id>270dadd7ea31c1bc43a0b1de118a30c2238171a8</id>
<content type='text'>
commit 4422829e8053068e0225e4d0ef42dc41ea7c9ef5 upstream.

array_index_nospec does not work for uint64_t on 32-bit builds.
However, the size of a memory slot must be less than 20 bits wide
on those system, since the memory slot must fit in the user
address space.  So just store it in an unsigned long.

Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 4422829e8053068e0225e4d0ef42dc41ea7c9ef5 upstream.

array_index_nospec does not work for uint64_t on 32-bit builds.
However, the size of a memory slot must be less than 20 bits wide
on those system, since the memory slot must fit in the user
address space.  So just store it in an unsigned long.

Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>RDMA/mlx4: Do not map the core_clock page to user space unless enabled</title>
<updated>2021-06-16T09:55:01+00:00</updated>
<author>
<name>Shay Drory</name>
<email>shayd@nvidia.com</email>
</author>
<published>2021-06-03T13:19:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6fe8d68e4ce966995c56e9d8b887dea43c92acbf'/>
<id>6fe8d68e4ce966995c56e9d8b887dea43c92acbf</id>
<content type='text'>
commit 404e5a12691fe797486475fe28cc0b80cb8bef2c upstream.

Currently when mlx4 maps the hca_core_clock page to the user space there
are read-modifiable registers, one of which is semaphore, on this page as
well as the clock counter. If user reads the wrong offset, it can modify
the semaphore and hang the device.

Do not map the hca_core_clock page to the user space unless the device has
been put in a backwards compatibility mode to support this feature.

After this patch, mlx4 core_clock won't be mapped to user space on the
majority of existing devices and the uverbs device time feature in
ibv_query_rt_values_ex() will be disabled.

Fixes: 52033cfb5aab ("IB/mlx4: Add mmap call to map the hardware clock")
Link: https://lore.kernel.org/r/9632304e0d6790af84b3b706d8c18732bc0d5e27.1622726305.git.leonro@nvidia.com
Signed-off-by: Shay Drory &lt;shayd@nvidia.com&gt;
Signed-off-by: Leon Romanovsky &lt;leonro@nvidia.com&gt;
Signed-off-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 404e5a12691fe797486475fe28cc0b80cb8bef2c upstream.

Currently when mlx4 maps the hca_core_clock page to the user space there
are read-modifiable registers, one of which is semaphore, on this page as
well as the clock counter. If user reads the wrong offset, it can modify
the semaphore and hang the device.

Do not map the hca_core_clock page to the user space unless the device has
been put in a backwards compatibility mode to support this feature.

After this patch, mlx4 core_clock won't be mapped to user space on the
majority of existing devices and the uverbs device time feature in
ibv_query_rt_values_ex() will be disabled.

Fixes: 52033cfb5aab ("IB/mlx4: Add mmap call to map the hardware clock")
Link: https://lore.kernel.org/r/9632304e0d6790af84b3b706d8c18732bc0d5e27.1622726305.git.leonro@nvidia.com
Signed-off-by: Shay Drory &lt;shayd@nvidia.com&gt;
Signed-off-by: Leon Romanovsky &lt;leonro@nvidia.com&gt;
Signed-off-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>usb: pd: Set PD_T_SINK_WAIT_CAP to 310ms</title>
<updated>2021-06-16T09:54:59+00:00</updated>
<author>
<name>Kyle Tso</name>
<email>kyletso@google.com</email>
</author>
<published>2021-05-28T08:16:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=17cd51099d8342873433f0f9d307d4384c020ff6'/>
<id>17cd51099d8342873433f0f9d307d4384c020ff6</id>
<content type='text'>
commit 6490fa565534fa83593278267785a694fd378a2b upstream.

Current timer PD_T_SINK_WAIT_CAP is set to 240ms which will violate the
SinkWaitCapTimer (tTypeCSinkWaitCap 310 - 620 ms) defined in the PD
Spec if the port is faster enough when running the state machine. Set it
to the lower bound 310ms to ensure the timeout is in Spec.

Fixes: f0690a25a140 ("staging: typec: USB Type-C Port Manager (tcpm)")
Cc: stable &lt;stable@vger.kernel.org&gt;
Reviewed-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Kyle Tso &lt;kyletso@google.com&gt;
Link: https://lore.kernel.org/r/20210528081613.730661-1-kyletso@google.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 6490fa565534fa83593278267785a694fd378a2b upstream.

Current timer PD_T_SINK_WAIT_CAP is set to 240ms which will violate the
SinkWaitCapTimer (tTypeCSinkWaitCap 310 - 620 ms) defined in the PD
Spec if the port is faster enough when running the state machine. Set it
to the lower bound 310ms to ensure the timeout is in Spec.

Fixes: f0690a25a140 ("staging: typec: USB Type-C Port Manager (tcpm)")
Cc: stable &lt;stable@vger.kernel.org&gt;
Reviewed-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Kyle Tso &lt;kyletso@google.com&gt;
Link: https://lore.kernel.org/r/20210528081613.730661-1-kyletso@google.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kvm: avoid speculation-based attacks from out-of-range memslot accesses</title>
<updated>2021-06-16T09:54:59+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2021-06-08T19:31:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=22b87fb17a28d37331bb9c1110737627b17f6781'/>
<id>22b87fb17a28d37331bb9c1110737627b17f6781</id>
<content type='text'>
commit da27a83fd6cc7780fea190e1f5c19e87019da65c upstream.

KVM's mechanism for accessing guest memory translates a guest physical
address (gpa) to a host virtual address using the right-shifted gpa
(also known as gfn) and a struct kvm_memory_slot.  The translation is
performed in __gfn_to_hva_memslot using the following formula:

      hva = slot-&gt;userspace_addr + (gfn - slot-&gt;base_gfn) * PAGE_SIZE

It is expected that gfn falls within the boundaries of the guest's
physical memory.  However, a guest can access invalid physical addresses
in such a way that the gfn is invalid.

__gfn_to_hva_memslot is called from kvm_vcpu_gfn_to_hva_prot, which first
retrieves a memslot through __gfn_to_memslot.  While __gfn_to_memslot
does check that the gfn falls within the boundaries of the guest's
physical memory or not, a CPU can speculate the result of the check and
continue execution speculatively using an illegal gfn. The speculation
can result in calculating an out-of-bounds hva.  If the resulting host
virtual address is used to load another guest physical address, this
is effectively a Spectre gadget consisting of two consecutive reads,
the second of which is data dependent on the first.

Right now it's not clear if there are any cases in which this is
exploitable.  One interesting case was reported by the original author
of this patch, and involves visiting guest page tables on x86.  Right
now these are not vulnerable because the hva read goes through get_user(),
which contains an LFENCE speculation barrier.  However, there are
patches in progress for x86 uaccess.h to mask kernel addresses instead of
using LFENCE; once these land, a guest could use speculation to read
from the VMM's ring 3 address space.  Other architectures such as ARM
already use the address masking method, and would be susceptible to
this same kind of data-dependent access gadgets.  Therefore, this patch
proactively protects from these attacks by masking out-of-bounds gfns
in __gfn_to_hva_memslot, which blocks speculation of invalid hvas.

Sean Christopherson noted that this patch does not cover
kvm_read_guest_offset_cached.  This however is limited to a few bytes
past the end of the cache, and therefore it is unlikely to be useful in
the context of building a chain of data dependent accesses.

Reported-by: Artemiy Margaritov &lt;artemiy.margaritov@gmail.com&gt;
Co-developed-by: Artemiy Margaritov &lt;artemiy.margaritov@gmail.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit da27a83fd6cc7780fea190e1f5c19e87019da65c upstream.

KVM's mechanism for accessing guest memory translates a guest physical
address (gpa) to a host virtual address using the right-shifted gpa
(also known as gfn) and a struct kvm_memory_slot.  The translation is
performed in __gfn_to_hva_memslot using the following formula:

      hva = slot-&gt;userspace_addr + (gfn - slot-&gt;base_gfn) * PAGE_SIZE

It is expected that gfn falls within the boundaries of the guest's
physical memory.  However, a guest can access invalid physical addresses
in such a way that the gfn is invalid.

__gfn_to_hva_memslot is called from kvm_vcpu_gfn_to_hva_prot, which first
retrieves a memslot through __gfn_to_memslot.  While __gfn_to_memslot
does check that the gfn falls within the boundaries of the guest's
physical memory or not, a CPU can speculate the result of the check and
continue execution speculatively using an illegal gfn. The speculation
can result in calculating an out-of-bounds hva.  If the resulting host
virtual address is used to load another guest physical address, this
is effectively a Spectre gadget consisting of two consecutive reads,
the second of which is data dependent on the first.

Right now it's not clear if there are any cases in which this is
exploitable.  One interesting case was reported by the original author
of this patch, and involves visiting guest page tables on x86.  Right
now these are not vulnerable because the hva read goes through get_user(),
which contains an LFENCE speculation barrier.  However, there are
patches in progress for x86 uaccess.h to mask kernel addresses instead of
using LFENCE; once these land, a guest could use speculation to read
from the VMM's ring 3 address space.  Other architectures such as ARM
already use the address masking method, and would be susceptible to
this same kind of data-dependent access gadgets.  Therefore, this patch
proactively protects from these attacks by masking out-of-bounds gfns
in __gfn_to_hva_memslot, which blocks speculation of invalid hvas.

Sean Christopherson noted that this patch does not cover
kvm_read_guest_offset_cached.  This however is limited to a few bytes
past the end of the cache, and therefore it is unlikely to be useful in
the context of building a chain of data dependent accesses.

Reported-by: Artemiy Margaritov &lt;artemiy.margaritov@gmail.com&gt;
Co-developed-by: Artemiy Margaritov &lt;artemiy.margaritov@gmail.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf/cgroups: Don't rotate events for cgroups unnecessarily</title>
<updated>2021-06-10T11:24:08+00:00</updated>
<author>
<name>Ian Rogers</name>
<email>irogers@google.com</email>
</author>
<published>2019-06-01T08:27:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0b4c9255a1d0d08fa8a2d8bc97302756d0e9e98d'/>
<id>0b4c9255a1d0d08fa8a2d8bc97302756d0e9e98d</id>
<content type='text'>
commit fd7d55172d1e2e501e6da0a5c1de25f06612dc2e upstream.

Currently perf_rotate_context assumes that if the context's nr_events !=
nr_active a rotation is necessary for perf event multiplexing. With
cgroups, nr_events is the total count of events for all cgroups and
nr_active will not include events in a cgroup other than the current
task's. This makes rotation appear necessary for cgroups when it is not.

Add a perf_event_context flag that is set when rotation is necessary.
Clear the flag during sched_out and set it when a flexible sched_in
fails due to resources.

Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Link: https://lkml.kernel.org/r/20190601082722.44543-1-irogers@google.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Wen Yang &lt;wenyang@linux.alibaba.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit fd7d55172d1e2e501e6da0a5c1de25f06612dc2e upstream.

Currently perf_rotate_context assumes that if the context's nr_events !=
nr_active a rotation is necessary for perf event multiplexing. With
cgroups, nr_events is the total count of events for all cgroups and
nr_active will not include events in a cgroup other than the current
task's. This makes rotation appear necessary for cgroups when it is not.

Add a perf_event_context flag that is set when rotation is necessary.
Clear the flag during sched_out and set it when a flexible sched_in
fails due to resources.

Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vince Weaver &lt;vincent.weaver@maine.edu&gt;
Link: https://lkml.kernel.org/r/20190601082722.44543-1-irogers@google.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Wen Yang &lt;wenyang@linux.alibaba.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
