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* Re: [PATCH] misc: hpilo: Fix use after free bug in ilo_remove due to race condition with ilo_open
@ 2023-04-30  1:11 kernel test robot
  0 siblings, 0 replies; 8+ messages in thread
From: kernel test robot @ 2023-04-30  1:11 UTC (permalink / raw)
  To: oe-kbuild; +Cc: lkp, Dan Carpenter

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20230417165246.467723-1-zyytlz.wz@163.com>
References: <20230417165246.467723-1-zyytlz.wz@163.com>
TO: Zheng Wang <zyytlz.wz@163.com>
TO: matt.hsiao@hpe.com
CC: arnd@arndb.de
CC: gregkh@linuxfoundation.org
CC: linux-kernel@vger.kernel.org
CC: hackerzheng666@gmail.com
CC: 1395428693sheep@gmail.com
CC: alex000young@gmail.com
CC: Zheng Wang <zyytlz.wz@163.com>

Hi Zheng,

kernel test robot noticed the following build warnings:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on char-misc/char-misc-next char-misc/char-misc-linus soc/for-next linus/master v6.3 next-20230428]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Zheng-Wang/misc-hpilo-Fix-use-after-free-bug-in-ilo_remove-due-to-race-condition-with-ilo_open/20230418-005502
base:   char-misc/char-misc-testing
patch link:    https://lore.kernel.org/r/20230417165246.467723-1-zyytlz.wz%40163.com
patch subject: [PATCH] misc: hpilo: Fix use after free bug in ilo_remove due  to race condition with ilo_open
:::::: branch date: 12 days ago
:::::: commit date: 12 days ago
config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20230430/202304300909.ALHN6Vry-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202304300909.ALHN6Vry-lkp@intel.com/

smatch warnings:
drivers/misc/hpilo.c:755 ilo_delete() warn: can 'ilo_hw' even be NULL?

vim +/ilo_hw +755 drivers/misc/hpilo.c

13a22f45e6cb1e Zheng Wang      2023-04-18  748  
13a22f45e6cb1e Zheng Wang      2023-04-18  749  static void ilo_delete(struct kref *kref)
13a22f45e6cb1e Zheng Wang      2023-04-18  750  {
13a22f45e6cb1e Zheng Wang      2023-04-18  751  	int i, minor;
13a22f45e6cb1e Zheng Wang      2023-04-18  752  	struct ilo_hwinfo *ilo_hw = container_of(kref, struct ilo_hwinfo, refcnt);
13a22f45e6cb1e Zheng Wang      2023-04-18  753  	struct pci_dev *pdev = ilo_hw->ilo_dev;
89bcb05d9bbf8b David Altobelli 2008-07-02  754  
ebf1b764aa5cb3 Mark Rusk       2012-11-06 @755  	if (!ilo_hw)
ebf1b764aa5cb3 Mark Rusk       2012-11-06  756  		return;
ebf1b764aa5cb3 Mark Rusk       2012-11-06  757  
89bcb05d9bbf8b David Altobelli 2008-07-02  758  	clear_device(ilo_hw);
89bcb05d9bbf8b David Altobelli 2008-07-02  759  
89bcb05d9bbf8b David Altobelli 2008-07-02  760  	minor = MINOR(ilo_hw->cdev.dev);
98dcd59dd063dd Camuso, Tony    2012-06-10  761  	for (i = minor; i < minor + max_ccb; i++)
89bcb05d9bbf8b David Altobelli 2008-07-02  762  		device_destroy(ilo_class, MKDEV(ilo_major, i));
89bcb05d9bbf8b David Altobelli 2008-07-02  763  
89bcb05d9bbf8b David Altobelli 2008-07-02  764  	cdev_del(&ilo_hw->cdev);
9f7048412163d8 David Altobelli 2009-08-17  765  	ilo_disable_interrupts(ilo_hw);
9f7048412163d8 David Altobelli 2009-08-17  766  	free_irq(pdev->irq, ilo_hw);
89bcb05d9bbf8b David Altobelli 2008-07-02  767  	ilo_unmap_device(pdev, ilo_hw);
89bcb05d9bbf8b David Altobelli 2008-07-02  768  	pci_release_regions(pdev);
bcdee04ea7ae04 Jiri Slaby      2012-09-13  769  	/*
bcdee04ea7ae04 Jiri Slaby      2012-09-13  770  	 * pci_disable_device(pdev) used to be here. But this PCI device has
bcdee04ea7ae04 Jiri Slaby      2012-09-13  771  	 * two functions with interrupt lines connected to a single pin. The
bcdee04ea7ae04 Jiri Slaby      2012-09-13  772  	 * other one is a USB host controller. So when we disable the PIN here
bcdee04ea7ae04 Jiri Slaby      2012-09-13  773  	 * e.g. by rmmod hpilo, the controller stops working. It is because
bcdee04ea7ae04 Jiri Slaby      2012-09-13  774  	 * the interrupt link is disabled in ACPI since it is not refcounted
bcdee04ea7ae04 Jiri Slaby      2012-09-13  775  	 * yet. See acpi_pci_link_free_irq called from acpi_pci_irq_disable.
bcdee04ea7ae04 Jiri Slaby      2012-09-13  776  	 */
89bcb05d9bbf8b David Altobelli 2008-07-02  777  	kfree(ilo_hw);
98dcd59dd063dd Camuso, Tony    2012-06-10  778  	ilo_hwdev[(minor / max_ccb)] = 0;
89bcb05d9bbf8b David Altobelli 2008-07-02  779  }
89bcb05d9bbf8b David Altobelli 2008-07-02  780  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH] misc: hpilo: Fix use after free bug in ilo_remove due  to race condition with ilo_open
@ 2023-04-17 16:52 Zheng Wang
  2023-04-17 17:43 ` Greg KH
  2023-05-02 11:46 ` Dan Carpenter
  0 siblings, 2 replies; 8+ messages in thread
From: Zheng Wang @ 2023-04-17 16:52 UTC (permalink / raw)
  To: matt.hsiao
  Cc: arnd, gregkh, linux-kernel, hackerzheng666, 1395428693sheep,
	alex000young, Zheng Wang

A race condition may occur if the user physically removes the ilo device 
while calling ilo_open.

If we remove the driver which will call ilo_remove to make cleanup, there 
is no guarantee to make sure there's no more ilo_open invoking.

The possible sequence is as follows:

Fix it by adding a refcount check to ilo_remove() function to free the 
"ilo_hwinfo " structure after the last file is closed.

CPU0                  CPU1

                    |ilo_open
ilo_remove          |
kfree(ilo_hw)       |
//free	            |
                    |hw = container_of(ip->i_cdev,
	   	     |struct ilo_hwinfo, cdev);
                    |hw->ccb_alloc[slot]
                    |//use
Fixes: 89bcb05d9bbf ("HP iLO driver")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
 drivers/misc/hpilo.c | 16 +++++++++++++++-
 drivers/misc/hpilo.h |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/hpilo.c b/drivers/misc/hpilo.c
index 8d00df9243c4..2e9af39e91a4 100644
--- a/drivers/misc/hpilo.c
+++ b/drivers/misc/hpilo.c
@@ -37,6 +37,8 @@ static const struct pci_device_id ilo_blacklist[] = {
 	{}
 };
 
+static void ilo_delete(struct kref *kref);
+
 static inline int get_entry_id(int entry)
 {
 	return (entry & ENTRY_MASK_DESCRIPTOR) >> ENTRY_BITPOS_DESCRIPTOR;
@@ -559,6 +561,7 @@ static int ilo_close(struct inode *ip, struct file *fp)
 		hw->ccb_alloc[slot]->ccb_cnt--;
 
 	spin_unlock(&hw->open_lock);
+	kref_put(&hw->refcnt, ilo_delete);
 
 	return 0;
 }
@@ -578,6 +581,7 @@ static int ilo_open(struct inode *ip, struct file *fp)
 	if (!data)
 		return -ENOMEM;
 
+	kref_get(&hw->refcnt);
 	spin_lock(&hw->open_lock);
 
 	/* each fd private_data holds sw/hw view of ccb */
@@ -633,6 +637,8 @@ static int ilo_open(struct inode *ip, struct file *fp)
 
 	if (!error)
 		fp->private_data = hw->ccb_alloc[slot];
+	else
+		kref_put(&hw->refcnt, ilo_delete);
 
 	return error;
 }
@@ -742,8 +748,15 @@ static int ilo_map_device(struct pci_dev *pdev, struct ilo_hwinfo *hw)
 
 static void ilo_remove(struct pci_dev *pdev)
 {
-	int i, minor;
 	struct ilo_hwinfo *ilo_hw = pci_get_drvdata(pdev);
+	kref_put(&ilo_hw->refcnt, ilo_delete);
+}
+
+static void ilo_delete(struct kref *kref)
+{
+	int i, minor;
+	struct ilo_hwinfo *ilo_hw = container_of(kref, struct ilo_hwinfo, refcnt);
+	struct pci_dev *pdev = ilo_hw->ilo_dev;
 
 	if (!ilo_hw)
 		return;
@@ -807,6 +820,7 @@ static int ilo_probe(struct pci_dev *pdev,
 		goto out;
 
 	ilo_hw->ilo_dev = pdev;
+	kref_init(&ilo_hw->refcnt);
 	spin_lock_init(&ilo_hw->alloc_lock);
 	spin_lock_init(&ilo_hw->fifo_lock);
 	spin_lock_init(&ilo_hw->open_lock);
diff --git a/drivers/misc/hpilo.h b/drivers/misc/hpilo.h
index d57c34680b09..ebc677eb45ae 100644
--- a/drivers/misc/hpilo.h
+++ b/drivers/misc/hpilo.h
@@ -62,6 +62,7 @@ struct ilo_hwinfo {
 	spinlock_t fifo_lock;
 
 	struct cdev cdev;
+	struct kref refcnt;
 };
 
 /* offset from mmio_vaddr for enabling doorbell interrupts */
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2023-05-05  7:35 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-04-30  1:11 [PATCH] misc: hpilo: Fix use after free bug in ilo_remove due to race condition with ilo_open kernel test robot
  -- strict thread matches above, loose matches on Subject: below --
2023-04-17 16:52 Zheng Wang
2023-04-17 17:43 ` Greg KH
2023-04-19  5:29   ` Zheng Hacker
2023-05-02 11:46 ` Dan Carpenter
2023-05-05  4:01   ` Zheng Hacker
2023-05-05  7:30     ` Dan Carpenter
2023-05-05  7:35       ` Zheng Hacker

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