<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/io_uring, branch v6.1.67</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>io_uring: fix off-by one bvec index</title>
<updated>2023-12-03T06:32:13+00:00</updated>
<author>
<name>Keith Busch</name>
<email>kbusch@kernel.org</email>
</author>
<published>2023-11-20T22:18:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=66ecd1cd8b0c79e65c490dc10c91d0428d95e594'/>
<id>66ecd1cd8b0c79e65c490dc10c91d0428d95e594</id>
<content type='text'>
commit d6fef34ee4d102be448146f24caf96d7b4a05401 upstream.

If the offset equals the bv_len of the first registered bvec, then the
request does not include any of that first bvec. Skip it so that drivers
don't have to deal with a zero length bvec, which was observed to break
NVMe's PRP list creation.

Cc: stable@vger.kernel.org
Fixes: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 d6fef34ee4d102be448146f24caf96d7b4a05401 upstream.

If the offset equals the bv_len of the first registered bvec, then the
request does not include any of that first bvec. Skip it so that drivers
don't have to deal with a zero length bvec, which was observed to break
NVMe's PRP list creation.

Cc: stable@vger.kernel.org
Fixes: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/fs: consider link-&gt;flags when getting path for LINKAT</title>
<updated>2023-12-03T06:32:11+00:00</updated>
<author>
<name>Charles Mirabile</name>
<email>cmirabil@redhat.com</email>
</author>
<published>2023-11-20T10:55:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b964a0a3910bbc133efae8840759f4ba17e1c222'/>
<id>b964a0a3910bbc133efae8840759f4ba17e1c222</id>
<content type='text'>
commit 8479063f1fbee201a8739130e816cc331b675838 upstream.

In order for `AT_EMPTY_PATH` to work as expected, the fact
that the user wants that behavior needs to make it to `getname_flags`
or it will return ENOENT.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc:  &lt;stable@vger.kernel.org&gt;
Link: https://github.com/axboe/liburing/issues/995
Signed-off-by: Charles Mirabile &lt;cmirabil@redhat.com&gt;
Link: https://lore.kernel.org/r/20231120105545.1209530-1-cmirabil@redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 8479063f1fbee201a8739130e816cc331b675838 upstream.

In order for `AT_EMPTY_PATH` to work as expected, the fact
that the user wants that behavior needs to make it to `getname_flags`
or it will return ENOENT.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc:  &lt;stable@vger.kernel.org&gt;
Link: https://github.com/axboe/liburing/issues/995
Signed-off-by: Charles Mirabile &lt;cmirabil@redhat.com&gt;
Link: https://lore.kernel.org/r/20231120105545.1209530-1-cmirabil@redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/net: ensure socket is marked connected on connect retry</title>
<updated>2023-11-20T10:52:18+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2023-11-03T16:35:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=129debbb4178b4f316e812c87815a4d5880ebd6e'/>
<id>129debbb4178b4f316e812c87815a4d5880ebd6e</id>
<content type='text'>
commit f8f9ab2d98116e79d220f1d089df7464ad4e026d upstream.

io_uring does non-blocking connection attempts, which can yield some
unexpected results if a connect request is re-attempted by an an
application. This is equivalent to the following sync syscall sequence:

sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
connect(sock, &amp;addr, sizeof(addr);

ret == -1 and errno == EINPROGRESS expected here. Now poll for POLLOUT
on sock, and when that returns, we expect the socket to be connected.
But if we follow that procedure with:

connect(sock, &amp;addr, sizeof(addr));

you'd expect ret == -1 and errno == EISCONN here, but you actually get
ret == 0. If we attempt the connection one more time, then we get EISCON
as expected.

io_uring used to do this, but turns out that bluetooth fails with EBADFD
if you attempt to re-connect. Also looks like EISCONN _could_ occur with
this sequence.

Retain the -&gt;in_progress logic, but work-around a potential EISCONN or
EBADFD error and only in those cases look at the sock_error(). This
should work in general and avoid the odd sequence of a repeated connect
request returning success when the socket is already connected.

This is all a side effect of the socket state being in a CONNECTING
state when we get EINPROGRESS, and only a re-connect or other related
operation will turn that into CONNECTED.

Cc: stable@vger.kernel.org
Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT")
Link: https://github.com/axboe/liburing/issues/980
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 f8f9ab2d98116e79d220f1d089df7464ad4e026d upstream.

io_uring does non-blocking connection attempts, which can yield some
unexpected results if a connect request is re-attempted by an an
application. This is equivalent to the following sync syscall sequence:

sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
connect(sock, &amp;addr, sizeof(addr);

ret == -1 and errno == EINPROGRESS expected here. Now poll for POLLOUT
on sock, and when that returns, we expect the socket to be connected.
But if we follow that procedure with:

connect(sock, &amp;addr, sizeof(addr));

you'd expect ret == -1 and errno == EISCONN here, but you actually get
ret == 0. If we attempt the connection one more time, then we get EISCON
as expected.

io_uring used to do this, but turns out that bluetooth fails with EBADFD
if you attempt to re-connect. Also looks like EISCONN _could_ occur with
this sequence.

Retain the -&gt;in_progress logic, but work-around a potential EISCONN or
EBADFD error and only in those cases look at the sock_error(). This
should work in general and avoid the odd sequence of a repeated connect
request returning success when the socket is already connected.

This is all a side effect of the socket state being in a CONNECTING
state when we get EINPROGRESS, and only a re-connect or other related
operation will turn that into CONNECTED.

Cc: stable@vger.kernel.org
Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT")
Link: https://github.com/axboe/liburing/issues/980
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/kbuf: Allow the full buffer id space for provided buffers</title>
<updated>2023-11-20T10:52:00+00:00</updated>
<author>
<name>Gabriel Krisman Bertazi</name>
<email>krisman@suse.de</email>
</author>
<published>2023-10-05T00:05:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=32b15fef33e8cd067eb4b1bbfa5c73c967b14f93'/>
<id>32b15fef33e8cd067eb4b1bbfa5c73c967b14f93</id>
<content type='text'>
[ Upstream commit f74c746e476b9dad51448b9a9421aae72b60e25f ]

nbufs tracks the number of buffers and not the last bgid. In 16-bit, we
have 2^16 valid buffers, but the check mistakenly rejects the last
bid. Let's fix it to make the interface consistent with the
documentation.

Fixes: ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/20231005000531.30800-3-krisman@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 f74c746e476b9dad51448b9a9421aae72b60e25f ]

nbufs tracks the number of buffers and not the last bgid. In 16-bit, we
have 2^16 valid buffers, but the check mistakenly rejects the last
bid. Let's fix it to make the interface consistent with the
documentation.

Fixes: ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/20231005000531.30800-3-krisman@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/kbuf: Fix check of BID wrapping in provided buffers</title>
<updated>2023-11-20T10:52:00+00:00</updated>
<author>
<name>Gabriel Krisman Bertazi</name>
<email>krisman@suse.de</email>
</author>
<published>2023-10-05T00:05:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=60db638be5f4eb6cecb1de86c545008784ccd749'/>
<id>60db638be5f4eb6cecb1de86c545008784ccd749</id>
<content type='text'>
[ Upstream commit ab69838e7c75b0edb699c1a8f42752b30333c46f ]

Commit 3851d25c75ed0 ("io_uring: check for rollover of buffer ID when
providing buffers") introduced a check to prevent wrapping the BID
counter when sqe-&gt;off is provided, but it's off-by-one too
restrictive, rejecting the last possible BID (65534).

i.e., the following fails with -EINVAL.

     io_uring_prep_provide_buffers(sqe, addr, size, 0xFFFF, 0, 0);

Fixes: 3851d25c75ed ("io_uring: check for rollover of buffer ID when providing buffers")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/20231005000531.30800-2-krisman@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 ab69838e7c75b0edb699c1a8f42752b30333c46f ]

Commit 3851d25c75ed0 ("io_uring: check for rollover of buffer ID when
providing buffers") introduced a check to prevent wrapping the BID
counter when sqe-&gt;off is provided, but it's off-by-one too
restrictive, rejecting the last possible BID (65534).

i.e., the following fails with -EINVAL.

     io_uring_prep_provide_buffers(sqe, addr, size, 0xFFFF, 0, 0);

Fixes: 3851d25c75ed ("io_uring: check for rollover of buffer ID when providing buffers")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/20231005000531.30800-2-krisman@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring: kiocb_done() should *not* trust -&gt;ki_pos if -&gt;{read,write}_iter() failed</title>
<updated>2023-11-08T13:11:02+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2023-08-28T22:47:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9eab5008db6c98273acaa0e0dde0fdb25848217e'/>
<id>9eab5008db6c98273acaa0e0dde0fdb25848217e</id>
<content type='text'>
[ Upstream commit 1939316bf988f3e49a07d9c4dd6f660bf4daa53d ]

-&gt;ki_pos value is unreliable in such cases.  For an obvious example,
consider O_DSYNC write - we feed the data to page cache and start IO,
then we make sure it's completed.  Update of -&gt;ki_pos is dealt with
by the first part; failure in the second ends up with negative value
returned _and_ -&gt;ki_pos left advanced as if sync had been successful.
In the same situation write(2) does not advance the file position
at all.

Reviewed-by: Christian Brauner &lt;brauner@kernel.org&gt;
Reviewed-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&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 1939316bf988f3e49a07d9c4dd6f660bf4daa53d ]

-&gt;ki_pos value is unreliable in such cases.  For an obvious example,
consider O_DSYNC write - we feed the data to page cache and start IO,
then we make sure it's completed.  Update of -&gt;ki_pos is dealt with
by the first part; failure in the second ends up with negative value
returned _and_ -&gt;ki_pos left advanced as if sync had been successful.
In the same situation write(2) does not advance the file position
at all.

Reviewed-by: Christian Brauner &lt;brauner@kernel.org&gt;
Reviewed-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid</title>
<updated>2023-11-02T08:35:29+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2023-10-28T13:30:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9236d2ea6465b37c0a73d994c1ad31753d31e5f5'/>
<id>9236d2ea6465b37c0a73d994c1ad31753d31e5f5</id>
<content type='text'>
commit 7644b1a1c9a7ae8ab99175989bfc8676055edb46 upstream.

We could race with SQ thread exit, and if we do, we'll hit a NULL pointer
dereference when the thread is cleared. Grab the SQPOLL data lock before
attempting to get the task cpu and pid for fdinfo, this ensures we have a
stable view of it.

Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032
Reviewed-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7644b1a1c9a7ae8ab99175989bfc8676055edb46 upstream.

We could race with SQ thread exit, and if we do, we'll hit a NULL pointer
dereference when the thread is cleared. Grab the SQPOLL data lock before
attempting to get the task cpu and pid for fdinfo, this ensures we have a
stable view of it.

Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032
Reviewed-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/fs: remove sqe-&gt;rw_flags checking from LINKAT</title>
<updated>2023-10-06T12:57:02+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2023-09-28T15:23:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=75c307d9f2fbb949cb8713b8f659fec5f21f2c34'/>
<id>75c307d9f2fbb949cb8713b8f659fec5f21f2c34</id>
<content type='text'>
commit a52d4f657568d6458e873f74a9602e022afe666f upstream.

This is unionized with the actual link flags, so they can of course be
set and they will be evaluated further down. If not we fail any LINKAT
that has to set option flags.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc: stable@vger.kernel.org
Reported-by: Thomas Leonard &lt;talex5@gmail.com&gt;
Link: https://github.com/axboe/liburing/issues/955
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 a52d4f657568d6458e873f74a9602e022afe666f upstream.

This is unionized with the actual link flags, so they can of course be
set and they will be evaluated further down. If not we fail any LINKAT
that has to set option flags.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc: stable@vger.kernel.org
Reported-by: Thomas Leonard &lt;talex5@gmail.com&gt;
Link: https://github.com/axboe/liburing/issues/955
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring/net: fix iter retargeting for selected buf</title>
<updated>2023-09-23T09:11:10+00:00</updated>
<author>
<name>Pavel Begunkov</name>
<email>asml.silence@gmail.com</email>
</author>
<published>2023-09-14T15:51:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6a1d1365fafe1b63e6c52ef72b40b1443a11f78c'/>
<id>6a1d1365fafe1b63e6c52ef72b40b1443a11f78c</id>
<content type='text'>
commit c21a8027ad8a68c340d0d58bf1cc61dcb0bc4d2f upstream.

When using selected buffer feature, io_uring delays data iter setup
until later. If io_setup_async_msg() is called before that it might see
not correctly setup iterator. Pre-init nr_segs and judge from its state
whether we repointing.

Cc: stable@vger.kernel.org
Reported-by: syzbot+a4c6e5ef999b68b26ed1@syzkaller.appspotmail.com
Fixes: 0455d4ccec548 ("io_uring: add POLL_FIRST support for send/sendmsg and recv/recvmsg")
Signed-off-by: Pavel Begunkov &lt;asml.silence@gmail.com&gt;
Link: https://lore.kernel.org/r/0000000000002770be06053c7757@google.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&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 c21a8027ad8a68c340d0d58bf1cc61dcb0bc4d2f upstream.

When using selected buffer feature, io_uring delays data iter setup
until later. If io_setup_async_msg() is called before that it might see
not correctly setup iterator. Pre-init nr_segs and judge from its state
whether we repointing.

Cc: stable@vger.kernel.org
Reported-by: syzbot+a4c6e5ef999b68b26ed1@syzkaller.appspotmail.com
Fixes: 0455d4ccec548 ("io_uring: add POLL_FIRST support for send/sendmsg and recv/recvmsg")
Signed-off-by: Pavel Begunkov &lt;asml.silence@gmail.com&gt;
Link: https://lore.kernel.org/r/0000000000002770be06053c7757@google.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io_uring: Don't set affinity on a dying sqpoll thread</title>
<updated>2023-09-19T10:27:54+00:00</updated>
<author>
<name>Pavel Begunkov</name>
<email>asml.silence@gmail.com</email>
</author>
<published>2023-09-12T13:57:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3e8b9b06de9d88e04f0a1daeab3ddf64af2e26a2'/>
<id>3e8b9b06de9d88e04f0a1daeab3ddf64af2e26a2</id>
<content type='text'>
From: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;

[ upstream commit bd6fc5da4c51107e1e0cec4a3a07963d1dae2c84 ]

Syzbot reported a null-ptr-deref of sqd-&gt;thread inside
io_sqpoll_wq_cpu_affinity.  It turns out the sqd-&gt;thread can go away
from under us during io_uring_register, in case the process gets a
fatal signal during io_uring_register.

It is not particularly hard to hit the race, and while I am not sure
this is the exact case hit by syzbot, it solves it.  Finally, checking
-&gt;thread is enough to close the race because we locked sqd while
"parking" the thread, thus preventing it from going away.

I reproduced it fairly consistently with a program that does:

int main(void) {
  ...
  io_uring_queue_init(RING_LEN, &amp;ring1, IORING_SETUP_SQPOLL);
  while (1) {
    io_uring_register_iowq_aff(ring, 1, &amp;mask);
  }
}

Executed in a loop with timeout to trigger SIGTERM:
  while true; do timeout 1 /a.out ; done

This will hit the following BUG() in very few attempts.

BUG: kernel NULL pointer dereference, address: 00000000000007a8
PGD 800000010e949067 P4D 800000010e949067 PUD 10e46e067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 15715 Comm: dead-sqpoll Not tainted 6.5.0-rc7-next-20230825-g193296236fa0-dirty #23
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:io_sqpoll_wq_cpu_affinity+0x27/0x70
Code: 90 90 90 0f 1f 44 00 00 55 53 48 8b 9f 98 03 00 00 48 85 db 74 4f
48 89 df 48 89 f5 e8 e2 f8 ff ff 48 8b 43 38 48 85 c0 74 22 &lt;48&gt; 8b b8
a8 07 00 00 48 89 ee e8 ba b1 00 00 48 89 df 89 c5 e8 70
RSP: 0018:ffffb04040ea7e70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff93c010749e40 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffffa7653331 RDI: 00000000ffffffff
RBP: ffffb04040ea7eb8 R08: 0000000000000000 R09: c0000000ffffdfff
R10: ffff93c01141b600 R11: ffffb04040ea7d18 R12: ffff93c00ea74840
R13: 0000000000000011 R14: 0000000000000000 R15: ffff93c00ea74800
FS:  00007fb7c276ab80(0000) GS:ffff93c36f200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000007a8 CR3: 0000000111634003 CR4: 0000000000370ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 ? __die_body+0x1a/0x60
 ? page_fault_oops+0x154/0x440
 ? do_user_addr_fault+0x174/0x7b0
 ? exc_page_fault+0x63/0x140
 ? asm_exc_page_fault+0x22/0x30
 ? io_sqpoll_wq_cpu_affinity+0x27/0x70
 __io_register_iowq_aff+0x2b/0x60
 __io_uring_register+0x614/0xa70
 __x64_sys_io_uring_register+0xaa/0x1a0
 do_syscall_64+0x3a/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
RIP: 0033:0x7fb7c226fec9
Code: 2e 00 b8 ca 00 00 00 0f 05 eb a5 66 0f 1f 44 00 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01
f0 ff ff 73 01 c3 48 8b 0d 97 7f 2d 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe2c0674f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb7c226fec9
RDX: 00007ffe2c067530 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007ffe2c0675d0 R08: 00007ffe2c067550 R09: 00007ffe2c067550
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe2c067750 R14: 0000000000000000 R15: 0000000000000000
 &lt;/TASK&gt;
Modules linked in:
CR2: 00000000000007a8
---[ end trace 0000000000000000 ]---

Reported-by: syzbot+c74fea926a78b8a91042@syzkaller.appspotmail.com
Fixes: ebdfefc09c6d ("io_uring/sqpoll: fix io-wq affinity when IORING_SETUP_SQPOLL is used")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/87v8cybuo6.fsf@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Pavel Begunkov &lt;asml.silence@gmail.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>
From: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;

[ upstream commit bd6fc5da4c51107e1e0cec4a3a07963d1dae2c84 ]

Syzbot reported a null-ptr-deref of sqd-&gt;thread inside
io_sqpoll_wq_cpu_affinity.  It turns out the sqd-&gt;thread can go away
from under us during io_uring_register, in case the process gets a
fatal signal during io_uring_register.

It is not particularly hard to hit the race, and while I am not sure
this is the exact case hit by syzbot, it solves it.  Finally, checking
-&gt;thread is enough to close the race because we locked sqd while
"parking" the thread, thus preventing it from going away.

I reproduced it fairly consistently with a program that does:

int main(void) {
  ...
  io_uring_queue_init(RING_LEN, &amp;ring1, IORING_SETUP_SQPOLL);
  while (1) {
    io_uring_register_iowq_aff(ring, 1, &amp;mask);
  }
}

Executed in a loop with timeout to trigger SIGTERM:
  while true; do timeout 1 /a.out ; done

This will hit the following BUG() in very few attempts.

BUG: kernel NULL pointer dereference, address: 00000000000007a8
PGD 800000010e949067 P4D 800000010e949067 PUD 10e46e067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 15715 Comm: dead-sqpoll Not tainted 6.5.0-rc7-next-20230825-g193296236fa0-dirty #23
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:io_sqpoll_wq_cpu_affinity+0x27/0x70
Code: 90 90 90 0f 1f 44 00 00 55 53 48 8b 9f 98 03 00 00 48 85 db 74 4f
48 89 df 48 89 f5 e8 e2 f8 ff ff 48 8b 43 38 48 85 c0 74 22 &lt;48&gt; 8b b8
a8 07 00 00 48 89 ee e8 ba b1 00 00 48 89 df 89 c5 e8 70
RSP: 0018:ffffb04040ea7e70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff93c010749e40 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffffa7653331 RDI: 00000000ffffffff
RBP: ffffb04040ea7eb8 R08: 0000000000000000 R09: c0000000ffffdfff
R10: ffff93c01141b600 R11: ffffb04040ea7d18 R12: ffff93c00ea74840
R13: 0000000000000011 R14: 0000000000000000 R15: ffff93c00ea74800
FS:  00007fb7c276ab80(0000) GS:ffff93c36f200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000007a8 CR3: 0000000111634003 CR4: 0000000000370ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 ? __die_body+0x1a/0x60
 ? page_fault_oops+0x154/0x440
 ? do_user_addr_fault+0x174/0x7b0
 ? exc_page_fault+0x63/0x140
 ? asm_exc_page_fault+0x22/0x30
 ? io_sqpoll_wq_cpu_affinity+0x27/0x70
 __io_register_iowq_aff+0x2b/0x60
 __io_uring_register+0x614/0xa70
 __x64_sys_io_uring_register+0xaa/0x1a0
 do_syscall_64+0x3a/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
RIP: 0033:0x7fb7c226fec9
Code: 2e 00 b8 ca 00 00 00 0f 05 eb a5 66 0f 1f 44 00 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01
f0 ff ff 73 01 c3 48 8b 0d 97 7f 2d 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe2c0674f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb7c226fec9
RDX: 00007ffe2c067530 RSI: 0000000000000011 RDI: 0000000000000003
RBP: 00007ffe2c0675d0 R08: 00007ffe2c067550 R09: 00007ffe2c067550
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe2c067750 R14: 0000000000000000 R15: 0000000000000000
 &lt;/TASK&gt;
Modules linked in:
CR2: 00000000000007a8
---[ end trace 0000000000000000 ]---

Reported-by: syzbot+c74fea926a78b8a91042@syzkaller.appspotmail.com
Fixes: ebdfefc09c6d ("io_uring/sqpoll: fix io-wq affinity when IORING_SETUP_SQPOLL is used")
Signed-off-by: Gabriel Krisman Bertazi &lt;krisman@suse.de&gt;
Link: https://lore.kernel.org/r/87v8cybuo6.fsf@suse.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Pavel Begunkov &lt;asml.silence@gmail.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
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