<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/security/keys/trusted-keys, branch v5.10.258</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.258</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v5.10.258'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-10-29T13:01:24+00:00</updated>
<entry>
<title>KEYS: trusted_tpm1: Compare HMAC values in constant time</title>
<updated>2025-10-29T13:01:24+00:00</updated>
<author>
<name>Eric Biggers</name>
<email>ebiggers@kernel.org</email>
</author>
<published>2025-10-20T16:26:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=e277dda06130267c3083da3661a60d8498d8deca'/>
<id>urn:sha1:e277dda06130267c3083da3661a60d8498d8deca</id>
<content type='text'>
[ Upstream commit eed0e3d305530066b4fc5370107cff8ef1a0d229 ]

To prevent timing attacks, HMAC value comparison needs to be constant
time.  Replace the memcmp() with the correct function, crypto_memneq().

[For the Fixes commit I used the commit that introduced the memcmp().
It predates the introduction of crypto_memneq(), but it was still a bug
at the time even though a helper function didn't exist yet.]

Fixes: d00a1c72f7f4 ("keys: add new trusted key-type")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
[ replaced crypto/utils.h include with crypto/algapi.h ]
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>security: keys: Modify mismatched function name</title>
<updated>2023-07-27T06:44:39+00:00</updated>
<author>
<name>Jiapeng Chong</name>
<email>jiapeng.chong@linux.alibaba.com</email>
</author>
<published>2023-06-14T02:18:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=5bc78ba88905fdd1f2fc4e848f0cdbb67fd7789b'/>
<id>urn:sha1:5bc78ba88905fdd1f2fc4e848f0cdbb67fd7789b</id>
<content type='text'>
[ Upstream commit 2a4152742025c5f21482e8cebc581702a0fa5b01 ]

No functional modification involved.

security/keys/trusted-keys/trusted_tpm2.c:203: warning: expecting prototype for tpm_buf_append_auth(). Prototype was for tpm2_buf_append_auth() instead.

Fixes: 2e19e10131a0 ("KEYS: trusted: Move TPM2 trusted keys code")
Reported-by: Abaci Robot &lt;abaci@linux.alibaba.com&gt;
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=5524
Signed-off-by: Jiapeng Chong &lt;jiapeng.chong@linux.alibaba.com&gt;
Reviewed-by: Paul Moore &lt;paul@paul-moore.com&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>KEYS: trusted: Fix memory leak on object td</title>
<updated>2021-05-19T08:12:50+00:00</updated>
<author>
<name>Colin Ian King</name>
<email>colin.king@canonical.com</email>
</author>
<published>2021-04-30T11:37:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=31c9a4b24d86cbb36ff0d7a085725a3b4f0138c8'/>
<id>urn:sha1:31c9a4b24d86cbb36ff0d7a085725a3b4f0138c8</id>
<content type='text'>
commit 83a775d5f9bfda95b1c295f95a3a041a40c7f321 upstream.

Two error return paths are neglecting to free allocated object td,
causing a memory leak. Fix this by returning via the error return
path that securely kfree's td.

Fixes clang scan-build warning:
security/keys/trusted-keys/trusted_tpm1.c:496:10: warning: Potential
memory leak [unix.Malloc]

Cc: stable@vger.kernel.org
Fixes: 5df16caada3f ("KEYS: trusted: Fix incorrect handling of tpm_get_random()")
Signed-off-by: Colin Ian King &lt;colin.king@canonical.com&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>security: keys: trusted: fix TPM2 authorizations</title>
<updated>2021-05-14T07:50:20+00:00</updated>
<author>
<name>James Bottomley</name>
<email>James.Bottomley@HansenPartnership.com</email>
</author>
<published>2021-01-27T19:06:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=09a119a2d4c05c98fab63d3976caa813b4a370a8'/>
<id>urn:sha1:09a119a2d4c05c98fab63d3976caa813b4a370a8</id>
<content type='text'>
[ Upstream commit de66514d934d70ce73c302ce0644b54970fc7196 ]

In TPM 1.2 an authorization was a 20 byte number.  The spec actually
recommended you to hash variable length passwords and use the sha1
hash as the authorization.  Because the spec doesn't require this
hashing, the current authorization for trusted keys is a 40 digit hex
number.  For TPM 2.0 the spec allows the passing in of variable length
passwords and passphrases directly, so we should allow that in trusted
keys for ease of use.  Update the 'blobauth' parameter to take this
into account, so we can now use plain text passwords for the keys.

so before

keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001" @u

after we will accept both the old hex sha1 form as well as a new
directly supplied password:

keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" @u

Since a sha1 hex code must be exactly 40 bytes long and a direct
password must be 20 or less, we use the length as the discriminator
for which form is input.

Note this is both and enhancement and a potential bug fix.  The TPM
2.0 spec requires us to strip leading zeros, meaning empyty
authorization is a zero length HMAC whereas we're currently passing in
20 bytes of zeros.  A lot of TPMs simply accept this as OK, but the
Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch
makes the Microsoft TPM emulator work with trusted keys.

Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips")
Signed-off-by: James Bottomley &lt;James.Bottomley@HansenPartnership.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Tested-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>KEYS: trusted: Fix TPM reservation for seal/unseal</title>
<updated>2021-04-28T11:39:59+00:00</updated>
<author>
<name>James Bottomley</name>
<email>James.Bottomley@HansenPartnership.com</email>
</author>
<published>2021-04-21T22:42:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=bf84ef2dd2ccdcd8f2658476d34b51455f970ce4'/>
<id>urn:sha1:bf84ef2dd2ccdcd8f2658476d34b51455f970ce4</id>
<content type='text'>
[ Upstream commit 9d5171eab462a63e2fbebfccf6026e92be018f20 ]

The original patch 8c657a0590de ("KEYS: trusted: Reserve TPM for seal
and unseal operations") was correct on the mailing list:

https://lore.kernel.org/linux-integrity/20210128235621.127925-4-jarkko@kernel.org/

But somehow got rebased so that the tpm_try_get_ops() in
tpm2_seal_trusted() got lost.  This causes an imbalanced put of the
TPM ops and causes oopses on TIS based hardware.

This fix puts back the lost tpm_try_get_ops()

Fixes: 8c657a0590de ("KEYS: trusted: Reserve TPM for seal and unseal operations")
Reported-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Acked-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Signed-off-by: James Bottomley &lt;James.Bottomley@HansenPartnership.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>KEYS: trusted: Reserve TPM for seal and unseal operations</title>
<updated>2021-03-04T10:38:29+00:00</updated>
<author>
<name>Jarkko Sakkinen</name>
<email>jarkko@kernel.org</email>
</author>
<published>2021-01-28T23:56:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=67118bb78d72aab5b831f054a74ae856339a1974'/>
<id>urn:sha1:67118bb78d72aab5b831f054a74ae856339a1974</id>
<content type='text'>
commit 8c657a0590de585b1115847c17b34a58025f2f4b upstream.

When TPM 2.0 trusted keys code was moved to the trusted keys subsystem,
the operations were unwrapped from tpm_try_get_ops() and tpm_put_ops(),
which are used to take temporarily the ownership of the TPM chip. The
ownership is only taken inside tpm_send(), but this is not sufficient,
as in the key load TPM2_CC_LOAD, TPM2_CC_UNSEAL and TPM2_FLUSH_CONTEXT
need to be done as a one single atom.

Take the TPM chip ownership before sending anything with
tpm_try_get_ops() and tpm_put_ops(), and use tpm_transmit_cmd() to send
TPM commands instead of tpm_send(), reverting back to the old behaviour.

Fixes: 2e19e10131a0 ("KEYS: trusted: Move TPM2 trusted keys code")
Reported-by: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: stable@vger.kernel.org
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Cc: Sumit Garg &lt;sumit.garg@linaro.org&gt;
Acked-by Sumit Garg &lt;sumit.garg@linaro.org&gt;
Tested-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>KEYS: trusted: Fix migratable=1 failing</title>
<updated>2021-03-04T10:38:29+00:00</updated>
<author>
<name>Jarkko Sakkinen</name>
<email>jarkko@kernel.org</email>
</author>
<published>2021-01-28T23:56:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=54c527c18e7fc4c00ee2c97d10c24ccdb07393aa'/>
<id>urn:sha1:54c527c18e7fc4c00ee2c97d10c24ccdb07393aa</id>
<content type='text'>
commit 8da7520c80468c48f981f0b81fc1be6599e3b0ad upstream.

Consider the following transcript:

$ keyctl add trusted kmk "new 32 blobauth=helloworld keyhandle=80000000 migratable=1" @u
add_key: Invalid argument

The documentation has the following description:

  migratable=   0|1 indicating permission to reseal to new PCR values,
                default 1 (resealing allowed)

The consequence is that "migratable=1" should succeed. Fix this by
allowing this condition to pass instead of return -EINVAL.

[*] Documentation/security/keys/trusted-encrypted.rst

Cc: stable@vger.kernel.org
Cc: "James E.J. Bottomley" &lt;jejb@linux.ibm.com&gt;
Cc: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Fixes: d00a1c72f7f4 ("keys: add new trusted key-type")
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>KEYS: trusted: Fix incorrect handling of tpm_get_random()</title>
<updated>2021-03-04T10:38:29+00:00</updated>
<author>
<name>Jarkko Sakkinen</name>
<email>jarkko@kernel.org</email>
</author>
<published>2021-01-28T23:56:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9d83cc1a1e7f494aedee2aa108e801d11525fccf'/>
<id>urn:sha1:9d83cc1a1e7f494aedee2aa108e801d11525fccf</id>
<content type='text'>
commit 5df16caada3fba3b21cb09b85cdedf99507f4ec1 upstream.

When tpm_get_random() was introduced, it defined the following API for the
return value:

1. A positive value tells how many bytes of random data was generated.
2. A negative value on error.

However, in the call sites the API was used incorrectly, i.e. as it would
only return negative values and otherwise zero. Returning he positive read
counts to the user space does not make any possible sense.

Fix this by returning -EIO when tpm_get_random() returns a positive value.

Fixes: 41ab999c80f1 ("tpm: Move tpm_get_random api into the TPM device driver")
Cc: stable@vger.kernel.org
Cc: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Cc: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Kent Yoder &lt;key@linux.vnet.ibm.com&gt;
Signed-off-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Reviewed-by: Mimi Zohar &lt;zohar@linux.ibm.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm, treewide: rename kzfree() to kfree_sensitive()</title>
<updated>2020-08-07T18:33:22+00:00</updated>
<author>
<name>Waiman Long</name>
<email>longman@redhat.com</email>
</author>
<published>2020-08-07T06:18:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=453431a54934d917153c65211b2dabf45562ca88'/>
<id>urn:sha1:453431a54934d917153c65211b2dabf45562ca88</id>
<content type='text'>
As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches &lt;joe@perches.com&gt;
Signed-off-by: Waiman Long &lt;longman@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Acked-by: David Howells &lt;dhowells@redhat.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Jarkko Sakkinen &lt;jarkko.sakkinen@linux.intel.com&gt;
Cc: James Morris &lt;jmorris@namei.org&gt;
Cc: "Serge E. Hallyn" &lt;serge@hallyn.com&gt;
Cc: Joe Perches &lt;joe@perches.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: "Jason A . Donenfeld" &lt;Jason@zx2c4.com&gt;
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>KEYS: Don't write out to userspace while holding key semaphore</title>
<updated>2020-03-29T11:40:41+00:00</updated>
<author>
<name>Waiman Long</name>
<email>longman@redhat.com</email>
</author>
<published>2020-03-22T01:11:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=d3ec10aa95819bff18a0d936b18884c7816d0914'/>
<id>urn:sha1:d3ec10aa95819bff18a0d936b18884c7816d0914</id>
<content type='text'>
A lockdep circular locking dependency report was seen when running a
keyutils test:

[12537.027242] ======================================================
[12537.059309] WARNING: possible circular locking dependency detected
[12537.088148] 4.18.0-147.7.1.el8_1.x86_64+debug #1 Tainted: G OE    --------- -  -
[12537.125253] ------------------------------------------------------
[12537.153189] keyctl/25598 is trying to acquire lock:
[12537.175087] 000000007c39f96c (&amp;mm-&gt;mmap_sem){++++}, at: __might_fault+0xc4/0x1b0
[12537.208365]
[12537.208365] but task is already holding lock:
[12537.234507] 000000003de5b58d (&amp;type-&gt;lock_class){++++}, at: keyctl_read_key+0x15a/0x220
[12537.270476]
[12537.270476] which lock already depends on the new lock.
[12537.270476]
[12537.307209]
[12537.307209] the existing dependency chain (in reverse order) is:
[12537.340754]
[12537.340754] -&gt; #3 (&amp;type-&gt;lock_class){++++}:
[12537.367434]        down_write+0x4d/0x110
[12537.385202]        __key_link_begin+0x87/0x280
[12537.405232]        request_key_and_link+0x483/0xf70
[12537.427221]        request_key+0x3c/0x80
[12537.444839]        dns_query+0x1db/0x5a5 [dns_resolver]
[12537.468445]        dns_resolve_server_name_to_ip+0x1e1/0x4d0 [cifs]
[12537.496731]        cifs_reconnect+0xe04/0x2500 [cifs]
[12537.519418]        cifs_readv_from_socket+0x461/0x690 [cifs]
[12537.546263]        cifs_read_from_socket+0xa0/0xe0 [cifs]
[12537.573551]        cifs_demultiplex_thread+0x311/0x2db0 [cifs]
[12537.601045]        kthread+0x30c/0x3d0
[12537.617906]        ret_from_fork+0x3a/0x50
[12537.636225]
[12537.636225] -&gt; #2 (root_key_user.cons_lock){+.+.}:
[12537.664525]        __mutex_lock+0x105/0x11f0
[12537.683734]        request_key_and_link+0x35a/0xf70
[12537.705640]        request_key+0x3c/0x80
[12537.723304]        dns_query+0x1db/0x5a5 [dns_resolver]
[12537.746773]        dns_resolve_server_name_to_ip+0x1e1/0x4d0 [cifs]
[12537.775607]        cifs_reconnect+0xe04/0x2500 [cifs]
[12537.798322]        cifs_readv_from_socket+0x461/0x690 [cifs]
[12537.823369]        cifs_read_from_socket+0xa0/0xe0 [cifs]
[12537.847262]        cifs_demultiplex_thread+0x311/0x2db0 [cifs]
[12537.873477]        kthread+0x30c/0x3d0
[12537.890281]        ret_from_fork+0x3a/0x50
[12537.908649]
[12537.908649] -&gt; #1 (&amp;tcp_ses-&gt;srv_mutex){+.+.}:
[12537.935225]        __mutex_lock+0x105/0x11f0
[12537.954450]        cifs_call_async+0x102/0x7f0 [cifs]
[12537.977250]        smb2_async_readv+0x6c3/0xc90 [cifs]
[12538.000659]        cifs_readpages+0x120a/0x1e50 [cifs]
[12538.023920]        read_pages+0xf5/0x560
[12538.041583]        __do_page_cache_readahead+0x41d/0x4b0
[12538.067047]        ondemand_readahead+0x44c/0xc10
[12538.092069]        filemap_fault+0xec1/0x1830
[12538.111637]        __do_fault+0x82/0x260
[12538.129216]        do_fault+0x419/0xfb0
[12538.146390]        __handle_mm_fault+0x862/0xdf0
[12538.167408]        handle_mm_fault+0x154/0x550
[12538.187401]        __do_page_fault+0x42f/0xa60
[12538.207395]        do_page_fault+0x38/0x5e0
[12538.225777]        page_fault+0x1e/0x30
[12538.243010]
[12538.243010] -&gt; #0 (&amp;mm-&gt;mmap_sem){++++}:
[12538.267875]        lock_acquire+0x14c/0x420
[12538.286848]        __might_fault+0x119/0x1b0
[12538.306006]        keyring_read_iterator+0x7e/0x170
[12538.327936]        assoc_array_subtree_iterate+0x97/0x280
[12538.352154]        keyring_read+0xe9/0x110
[12538.370558]        keyctl_read_key+0x1b9/0x220
[12538.391470]        do_syscall_64+0xa5/0x4b0
[12538.410511]        entry_SYSCALL_64_after_hwframe+0x6a/0xdf
[12538.435535]
[12538.435535] other info that might help us debug this:
[12538.435535]
[12538.472829] Chain exists of:
[12538.472829]   &amp;mm-&gt;mmap_sem --&gt; root_key_user.cons_lock --&gt; &amp;type-&gt;lock_class
[12538.472829]
[12538.524820]  Possible unsafe locking scenario:
[12538.524820]
[12538.551431]        CPU0                    CPU1
[12538.572654]        ----                    ----
[12538.595865]   lock(&amp;type-&gt;lock_class);
[12538.613737]                                lock(root_key_user.cons_lock);
[12538.644234]                                lock(&amp;type-&gt;lock_class);
[12538.672410]   lock(&amp;mm-&gt;mmap_sem);
[12538.687758]
[12538.687758]  *** DEADLOCK ***
[12538.687758]
[12538.714455] 1 lock held by keyctl/25598:
[12538.732097]  #0: 000000003de5b58d (&amp;type-&gt;lock_class){++++}, at: keyctl_read_key+0x15a/0x220
[12538.770573]
[12538.770573] stack backtrace:
[12538.790136] CPU: 2 PID: 25598 Comm: keyctl Kdump: loaded Tainted: G
[12538.844855] Hardware name: HP ProLiant DL360 Gen9/ProLiant DL360 Gen9, BIOS P89 12/27/2015
[12538.881963] Call Trace:
[12538.892897]  dump_stack+0x9a/0xf0
[12538.907908]  print_circular_bug.isra.25.cold.50+0x1bc/0x279
[12538.932891]  ? save_trace+0xd6/0x250
[12538.948979]  check_prev_add.constprop.32+0xc36/0x14f0
[12538.971643]  ? keyring_compare_object+0x104/0x190
[12538.992738]  ? check_usage+0x550/0x550
[12539.009845]  ? sched_clock+0x5/0x10
[12539.025484]  ? sched_clock_cpu+0x18/0x1e0
[12539.043555]  __lock_acquire+0x1f12/0x38d0
[12539.061551]  ? trace_hardirqs_on+0x10/0x10
[12539.080554]  lock_acquire+0x14c/0x420
[12539.100330]  ? __might_fault+0xc4/0x1b0
[12539.119079]  __might_fault+0x119/0x1b0
[12539.135869]  ? __might_fault+0xc4/0x1b0
[12539.153234]  keyring_read_iterator+0x7e/0x170
[12539.172787]  ? keyring_read+0x110/0x110
[12539.190059]  assoc_array_subtree_iterate+0x97/0x280
[12539.211526]  keyring_read+0xe9/0x110
[12539.227561]  ? keyring_gc_check_iterator+0xc0/0xc0
[12539.249076]  keyctl_read_key+0x1b9/0x220
[12539.266660]  do_syscall_64+0xa5/0x4b0
[12539.283091]  entry_SYSCALL_64_after_hwframe+0x6a/0xdf

One way to prevent this deadlock scenario from happening is to not
allow writing to userspace while holding the key semaphore. Instead,
an internal buffer is allocated for getting the keys out from the
read method first before copying them out to userspace without holding
the lock.

That requires taking out the __user modifier from all the relevant
read methods as well as additional changes to not use any userspace
write helpers. That is,

  1) The put_user() call is replaced by a direct copy.
  2) The copy_to_user() call is replaced by memcpy().
  3) All the fault handling code is removed.

Compiling on a x86-64 system, the size of the rxrpc_read() function is
reduced from 3795 bytes to 2384 bytes with this patch.

Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Jarkko Sakkinen &lt;jarkko.sakkinen@linux.intel.com&gt;
Signed-off-by: Waiman Long &lt;longman@redhat.com&gt;
Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
</content>
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