/* 32-bit compatibility syscall for 64-bit systems
 *
 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/syscalls.h>
#include <linux/keyctl.h>
#include <linux/compat.h>
#include <linux/slab.h>
#include "internal.h"

/*
 * Instantiate a key with the specified compatibility multipart payload and
 * link the key into the destination keyring if one is given.
 *
 * The caller must have the appropriate instantiation permit set for this to
 * work (see keyctl_assume_authority).  No other permissions are required.
 *
 * If successful, 0 will be returned.
 */
static long compat_keyctl_instantiate_key_iov(
	key_serial_t id,
	const struct compat_iovec __user *_payload_iov,
	unsigned ioc,
	key_serial_t ringid)
{
	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
	struct iov_iter from;
	long ret;

	if (!_payload_iov)
		ioc = 0;

	ret = compat_import_iovec(WRITE, _payload_iov, ioc,
				  ARRAY_SIZE(iovstack), &iov,
				  &from);
	if (ret < 0)
		return ret;

	ret = keyctl_instantiate_key_common(id, &from, ringid);
	kfree(iov);
	return ret;
}

/*
 * The key control system call, 32-bit compatibility version for 64-bit archs
 *
 * This should only be called if the 64-bit arch uses weird pointers in 32-bit
 * mode or doesn't guarantee that the top 32-bits of the argument registers on
 * taking a 32-bit syscall are zero.  If you can, you should call sys_keyctl()
 * directly.
 */
COMPAT_SYSCALL_DEFINE5(keyctl, u32, option,
		       u32, arg2, u32, arg3, u32, arg4, u32, arg5)
{
	switch (option) {
	case KEYCTL_GET_KEYRING_ID:
		return keyctl_get_keyring_ID(arg2, arg3);

	case KEYCTL_JOIN_SESSION_KEYRING:
		return keyctl_join_session_keyring(compat_ptr(arg2));

	case KEYCTL_UPDATE:
		return keyctl_update_key(arg2, compat_ptr(arg3), arg4);

	case KEYCTL_REVOKE:
		return keyctl_revoke_key(arg2);

	case KEYCTL_DESCRIBE:
		return keyctl_describe_key(arg2, compat_ptr(arg3), arg4);

	case KEYCTL_CLEAR:
		return keyctl_keyring_clear(arg2);

	case KEYCTL_LINK:
		return keyctl_keyring_link(arg2, arg3);

	case KEYCTL_UNLINK:
		return keyctl_keyring_unlink(arg2, arg3);

	case KEYCTL_SEARCH:
		return keyctl_keyring_search(arg2, compat_ptr(arg3),
					     compat_ptr(arg4), arg5);

	case KEYCTL_READ:
		return keyctl_read_key(arg2, compat_ptr(arg3), arg4);

	case KEYCTL_CHOWN:
		return keyctl_chown_key(arg2, arg3, arg4);

	case KEYCTL_SETPERM:
		return keyctl_setperm_key(arg2, arg3);

	case KEYCTL_INSTANTIATE:
		return keyctl_instantiate_key(arg2, compat_ptr(arg3), arg4,
					      arg5);

	case KEYCTL_NEGATE:
		return keyctl_negate_key(arg2, arg3, arg4);

	case KEYCTL_SET_REQKEY_KEYRING:
		return keyctl_set_reqkey_keyring(arg2);

	case KEYCTL_SET_TIMEOUT:
		return keyctl_set_timeout(arg2, arg3);

	case KEYCTL_ASSUME_AUTHORITY:
		return keyctl_assume_authority(arg2);

	case KEYCTL_GET_SECURITY:
		return keyctl_get_security(arg2, compat_ptr(arg3), arg4);

	case KEYCTL_SESSION_TO_PARENT:
		return keyctl_session_to_parent();

	case KEYCTL_REJECT:
		return keyctl_reject_key(arg2, arg3, arg4, arg5);

	case KEYCTL_INSTANTIATE_IOV:
		return compat_keyctl_instantiate_key_iov(
			arg2, compat_ptr(arg3), arg4, arg5);

	case KEYCTL_INVALIDATE:
		return keyctl_invalidate_key(arg2);

	case KEYCTL_GET_PERSISTENT:
		return keyctl_get_persistent(arg2, arg3);

	case KEYCTL_DH_COMPUTE:
		return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3),
					 arg4, compat_ptr(arg5));

	default:
		return -EOPNOTSUPP;
	}
}
eft'>Lines</th></tr>
6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/kvm/kvm_stat/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/kvm/kvm_stat/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/kvm/kvm_stat/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>tools/kvm/kvm_stat/Makefile</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/kvm/kvm_stat/Makefile?id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/kvm/kvm_stat/Makefile?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'tools/kvm/kvm_stat/Makefile')</div><table summary='diffstat' class='diffstat'>