[PATCH v4] drm/radeon/radeon_kms: Fix a NULL pointer dereference in radeon_driver_open_kms()
Qingyang Zhou
zhou1615 at umn.edu
Wed Dec 1 12:48:47 UTC 2021
Hi Christian:
The warning is from the kernel test robot, I quote it here. The key point
is that vm may be used in radeon_vm_fini(rdev, vm) without initialization.
Although it is not possible in practice, I still add initializations to
silence the warning of llvm.
---------- Forwarded message ---------
From: kernel test robot <lkp at intel.com>
Date: Wed, Dec 1, 2021 at 4:32 AM
Subject: drivers/gpu/drm/radeon/radeon_kms.c:672:7: warning: variable 'vm'
is used uninitialized whenever 'if' condition is false
To: Zhou Qingyang <zhou1615 at umn.edu>
Cc: <llvm at lists.linux.dev>, <kbuild-all at lists.01.org>, <
linux-kernel at vger.kernel.org>, 0day robot <lkp at intel.com>
tree:
https://github.com/0day-ci/linux/commits/UPDATE-20211130-233655/Zhou-Qingyang/drm-radeon-radeon_kms-Fix-a-NULL-pointer-dereference-in-radeon_driver_open_kms/20211130-231509
head: 123fb3d217e89c4388fdb08b63991bac7c324219
commit: 123fb3d217e89c4388fdb08b63991bac7c324219 drm/radeon/radeon_kms: Fix
a NULL pointer dereference in radeon_driver_open_kms()
date: 5 hours ago
config: mips-randconfig-r014-20211128 (
https://download.01.org/0day-ci/archive/20211201/202112010420.xkXHciHS-lkp@intel.com/config
)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
25eb7fa01d7ebbe67648ea03841cda55b4239ab2)
reproduce (this is a W=1 build):
wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
#
https://github.com/0day-ci/linux/commit/123fb3d217e89c4388fdb08b63991bac7c324219
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review
UPDATE-20211130-233655/Zhou-Qingyang/drm-radeon-radeon_kms-Fix-a-NULL-pointer-dereference-in-radeon_driver_open_kms/20211130-231509
git checkout 123fb3d217e89c4388fdb08b63991bac7c324219
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1
O=build_dir ARCH=mips SHELL=/bin/bash drivers/gpu/drm/radeon/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>
All warnings (new ones prefixed by >>):
>> drivers/gpu/drm/radeon/radeon_kms.c:672:7: warning: variable 'vm' is
used uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
if (rdev->accel_working) {
^~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_kms.c:705:23: note: uninitialized use
occurs here
radeon_vm_fini(rdev, vm);
^~
drivers/gpu/drm/radeon/radeon_kms.c:672:3: note: remove the 'if' if its
condition is always true
if (rdev->accel_working) {
^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_kms.c:664:6: warning: variable 'vm' is
used uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
if (rdev->family >= CHIP_CAYMAN) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_kms.c:705:23: note: uninitialized use
occurs here
radeon_vm_fini(rdev, vm);
^~
drivers/gpu/drm/radeon/radeon_kms.c:664:2: note: remove the 'if' if its
condition is always true
if (rdev->family >= CHIP_CAYMAN) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/radeon_kms.c:653:22: note: initialize the
variable 'vm' to silence this warning
struct radeon_vm *vm;
^
= NULL
2 warnings generated.
vim +672 drivers/gpu/drm/radeon/radeon_kms.c
771fe6b912fca54 Jerome Glisse 2009-06-05 638
f482a1419545ded Alex Deucher 2012-07-17 639 /**
f482a1419545ded Alex Deucher 2012-07-17 640 *
radeon_driver_open_kms - drm callback for open
f482a1419545ded Alex Deucher 2012-07-17 641 *
f482a1419545ded Alex Deucher 2012-07-17 642 * @dev: drm dev pointer
f482a1419545ded Alex Deucher 2012-07-17 643 * @file_priv: drm file
f482a1419545ded Alex Deucher 2012-07-17 644 *
f482a1419545ded Alex Deucher 2012-07-17 645 * On device open, init
vm on cayman+ (all asics).
f482a1419545ded Alex Deucher 2012-07-17 646 * Returns 0 on
success, error on failure.
f482a1419545ded Alex Deucher 2012-07-17 647 */
771fe6b912fca54 Jerome Glisse 2009-06-05 648 int
radeon_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
771fe6b912fca54 Jerome Glisse 2009-06-05 649 {
721604a15b934f0 Jerome Glisse 2012-01-05 650 struct
radeon_device *rdev = dev->dev_private;
10ebc0bc09344ab Dave Airlie 2012-09-17 651 int r;
123fb3d217e89c4 Zhou Qingyang 2021-11-30 652 struct radeon_fpriv
*fpriv;
123fb3d217e89c4 Zhou Qingyang 2021-11-30 653 struct radeon_vm
*vm;
721604a15b934f0 Jerome Glisse 2012-01-05 654
721604a15b934f0 Jerome Glisse 2012-01-05 655
file_priv->driver_priv = NULL;
721604a15b934f0 Jerome Glisse 2012-01-05 656
10ebc0bc09344ab Dave Airlie 2012-09-17 657 r =
pm_runtime_get_sync(dev->dev);
9fb10671011143d Aditya Pakki 2020-06-13 658 if (r < 0) {
9fb10671011143d Aditya Pakki 2020-06-13 659
pm_runtime_put_autosuspend(dev->dev);
10ebc0bc09344ab Dave Airlie 2012-09-17 660 return r;
9fb10671011143d Aditya Pakki 2020-06-13 661 }
10ebc0bc09344ab Dave Airlie 2012-09-17 662
721604a15b934f0 Jerome Glisse 2012-01-05 663 /* new gpu have
virtual address space support */
721604a15b934f0 Jerome Glisse 2012-01-05 664 if (rdev->family >=
CHIP_CAYMAN) {
721604a15b934f0 Jerome Glisse 2012-01-05 665
721604a15b934f0 Jerome Glisse 2012-01-05 666 fpriv =
kzalloc(sizeof(*fpriv), GFP_KERNEL);
721604a15b934f0 Jerome Glisse 2012-01-05 667 if
(unlikely(!fpriv)) {
32c59dc14b72803 Alex Deucher 2016-08-31 668 r =
-ENOMEM;
32c59dc14b72803 Alex Deucher 2016-08-31 669
goto out_suspend;
721604a15b934f0 Jerome Glisse 2012-01-05 670 }
721604a15b934f0 Jerome Glisse 2012-01-05 671
544143f9e01a60a Alex Deucher 2015-01-28 @672 if
(rdev->accel_working) {
cc9e67e3d7000c1 Christian König 2014-07-18 673 vm
= &fpriv->vm;
cc9e67e3d7000c1 Christian König 2014-07-18 674 r =
radeon_vm_init(rdev, vm);
74073c9dd299056 Quentin Casasnovas 2014-03-18 675 if
(r) {
123fb3d217e89c4 Zhou Qingyang 2021-11-30 676
goto out_fpriv;
74073c9dd299056 Quentin Casasnovas 2014-03-18 677 }
d72d43cfc5847c1 Christian König 2012-10-09 678
f1e3dc708aaadb9 Christian König 2014-02-20 679 r =
radeon_bo_reserve(rdev->ring_tmp_bo.bo, false);
74073c9dd299056 Quentin Casasnovas 2014-03-18 680 if
(r) {
123fb3d217e89c4 Zhou Qingyang 2021-11-30 681
goto out_vm_fini;
74073c9dd299056 Quentin Casasnovas 2014-03-18 682 }
f1e3dc708aaadb9 Christian König 2014-02-20 683
d72d43cfc5847c1 Christian König 2012-10-09 684 /*
map the ib pool buffer read only into
d72d43cfc5847c1 Christian König 2012-10-09 685 *
virtual address space */
cc9e67e3d7000c1 Christian König 2014-07-18 686
vm->ib_bo_va = radeon_vm_bo_add(rdev, vm,
d72d43cfc5847c1 Christian König 2012-10-09 687
rdev->ring_tmp_bo.bo);
123fb3d217e89c4 Zhou Qingyang 2021-11-30 688 if
(!vm->ib_bo_va) {
123fb3d217e89c4 Zhou Qingyang 2021-11-30 689
r = -ENOMEM;
123fb3d217e89c4 Zhou Qingyang 2021-11-30 690
goto out_vm_fini;
123fb3d217e89c4 Zhou Qingyang 2021-11-30 691 }
123fb3d217e89c4 Zhou Qingyang 2021-11-30 692
cc9e67e3d7000c1 Christian König 2014-07-18 693 r =
radeon_vm_bo_set_addr(rdev, vm->ib_bo_va,
cc9e67e3d7000c1 Christian König 2014-07-18 694
RADEON_VA_IB_OFFSET,
d72d43cfc5847c1 Christian König 2012-10-09 695
RADEON_VM_PAGE_READABLE |
d72d43cfc5847c1 Christian König 2012-10-09 696
RADEON_VM_PAGE_SNOOPED);
721604a15b934f0 Jerome Glisse 2012-01-05 697 if
(r) {
123fb3d217e89c4 Zhou Qingyang 2021-11-30 698
goto out_vm_fini;
721604a15b934f0 Jerome Glisse 2012-01-05 699 }
24f47acc78b0ab5 Jérôme Glisse 2014-05-07 700 }
721604a15b934f0 Jerome Glisse 2012-01-05 701
file_priv->driver_priv = fpriv;
721604a15b934f0 Jerome Glisse 2012-01-05 702 }
10ebc0bc09344ab Dave Airlie 2012-09-17 703
123fb3d217e89c4 Zhou Qingyang 2021-11-30 704 out_vm_fini:
123fb3d217e89c4 Zhou Qingyang 2021-11-30 705
radeon_vm_fini(rdev, vm);
123fb3d217e89c4 Zhou Qingyang 2021-11-30 706 out_fpriv:
123fb3d217e89c4 Zhou Qingyang 2021-11-30 707 kfree(fpriv);
32c59dc14b72803 Alex Deucher 2016-08-31 708 out_suspend:
10ebc0bc09344ab Dave Airlie 2012-09-17 709
pm_runtime_mark_last_busy(dev->dev);
10ebc0bc09344ab Dave Airlie 2012-09-17 710
pm_runtime_put_autosuspend(dev->dev);
32c59dc14b72803 Alex Deucher 2016-08-31 711 return r;
771fe6b912fca54 Jerome Glisse 2009-06-05 712 }
771fe6b912fca54 Jerome Glisse 2009-06-05 713
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
On Wed, Dec 1, 2021 at 3:20 PM Christian König <christian.koenig at amd.com>
wrote:
> Am 01.12.21 um 04:22 schrieb Zhou Qingyang:
> > In radeon_driver_open_kms(), radeon_vm_bo_add() is assigned to
> > vm->ib_bo_va and passes and used in radeon_vm_bo_set_addr(). In
> > radeon_vm_bo_set_addr(), there is a dereference of vm->ib_bo_va,
> > which could lead to a NULL pointer dereference on failure of
> > radeon_vm_bo_add().
> >
> > Fix this bug by adding a check of vm->ib_bo_va.
> >
> > This bug was found by a static analyzer. The analysis employs
> > differential checking to identify inconsistent security operations
> > (e.g., checks or kfrees) between two code paths and confirms that the
> > inconsistent operations are not recovered in the current function or
> > the callers, so they constitute bugs.
> >
> > Note that, as a bug found by static analysis, it can be a false
> > positive or hard to trigger. Multiple researchers have cross-reviewed
> > the bug.
> >
> > Builds with CONFIG_DRM_RADEON=m show no new warnings,
> > and our static analyzer no longer warns about this code.
> >
> > Fixes: cc9e67e3d700 ("drm/radeon: fix VM IB handling")
> > Reported-by: kernel test robot <lkp at intel.com>
> > Signed-off-by: Zhou Qingyang <zhou1615 at umn.edu>
> > ---
> > Changes in v2:
> > - Initialize the variables to silence warning
>
> What warning do you get? Double checking the code that shouldn't be
> necessary and is usually rather frowned upon.
>
> Thanks,
> Christian.
>
> >
> > Changes in v3:
> > - Fix the bug that good case will also be freed
> > - Improve code style
> >
> > Changes in v2:
> > - Improve the error handling into goto style
> >
> > drivers/gpu/drm/radeon/radeon_kms.c | 37 ++++++++++++++++-------------
> > 1 file changed, 20 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_kms.c
> b/drivers/gpu/drm/radeon/radeon_kms.c
> > index 482fb0ae6cb5..9d0f840286a1 100644
> > --- a/drivers/gpu/drm/radeon/radeon_kms.c
> > +++ b/drivers/gpu/drm/radeon/radeon_kms.c
> > @@ -648,7 +648,9 @@ void radeon_driver_lastclose_kms(struct drm_device
> *dev)
> > int radeon_driver_open_kms(struct drm_device *dev, struct drm_file
> *file_priv)
> > {
> > struct radeon_device *rdev = dev->dev_private;
> > - int r;
> > + struct radeon_fpriv *fpriv = NULL;
> > + struct radeon_vm *vm = NULL;
> > + int r = 0;
> >
> > file_priv->driver_priv = NULL;
> >
> > @@ -660,8 +662,6 @@ int radeon_driver_open_kms(struct drm_device *dev,
> struct drm_file *file_priv)
> >
> > /* new gpu have virtual address space support */
> > if (rdev->family >= CHIP_CAYMAN) {
> > - struct radeon_fpriv *fpriv;
> > - struct radeon_vm *vm;
> >
> > fpriv = kzalloc(sizeof(*fpriv), GFP_KERNEL);
> > if (unlikely(!fpriv)) {
> > @@ -672,35 +672,38 @@ int radeon_driver_open_kms(struct drm_device *dev,
> struct drm_file *file_priv)
> > if (rdev->accel_working) {
> > vm = &fpriv->vm;
> > r = radeon_vm_init(rdev, vm);
> > - if (r) {
> > - kfree(fpriv);
> > - goto out_suspend;
> > - }
> > + if (r)
> > + goto out_fpriv;
> >
> > r = radeon_bo_reserve(rdev->ring_tmp_bo.bo,
> false);
> > - if (r) {
> > - radeon_vm_fini(rdev, vm);
> > - kfree(fpriv);
> > - goto out_suspend;
> > - }
> > + if (r)
> > + goto out_vm_fini;
> >
> > /* map the ib pool buffer read only into
> > * virtual address space */
> > vm->ib_bo_va = radeon_vm_bo_add(rdev, vm,
> > rdev->
> ring_tmp_bo.bo);
> > + if (!vm->ib_bo_va) {
> > + r = -ENOMEM;
> > + goto out_vm_fini;
> > + }
> > +
> > r = radeon_vm_bo_set_addr(rdev, vm->ib_bo_va,
> > RADEON_VA_IB_OFFSET,
> > RADEON_VM_PAGE_READABLE |
> > RADEON_VM_PAGE_SNOOPED);
> > - if (r) {
> > - radeon_vm_fini(rdev, vm);
> > - kfree(fpriv);
> > - goto out_suspend;
> > - }
> > + if (r)
> > + goto out_vm_fini;
> > }
> > file_priv->driver_priv = fpriv;
> > }
> >
> > +out_vm_fini:
> > + if (r)
> > + radeon_vm_fini(rdev, vm);
> > +out_fpriv:
> > + if (r)
> > + kfree(fpriv);
> > out_suspend:
> > pm_runtime_mark_last_busy(dev->dev);
> > pm_runtime_put_autosuspend(dev->dev);
>
>
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