Patch "cxl: Avoid double free_irq() for psl,slice interrupts" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

cxl: Avoid double free_irq() for psl,slice interrupts

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cxl-avoid-double-free_irq-for-psl-slice-interrupts.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Vaibhav Jain <[email protected]>
Date: Fri, 2 Jun 2017 22:26:48 +0530
Subject: cxl: Avoid double free_irq() for psl,slice interrupts

From: Vaibhav Jain <[email protected]>

commit b3aa20ba2ba8072b73bd799605b8c98927b7056c upstream.

During an eeh call to cxl_remove can result in double free_irq of psl,slice interrupts. This can happen if perst_reloads_same_image == 1 and call to cxl_configure_adapter() fails during slot_reset callback. In such a case we see a kernel oops with following back-trace:

Oops: Kernel access of bad area, sig: 11 [#1]
Call Trace:
  free_irq+0x88/0xd0 (unreliable)
  cxl_unmap_irq+0x20/0x40 [cxl]
  cxl_native_release_psl_irq+0x78/0xd8 [cxl]
  pci_deconfigure_afu+0xac/0x110 [cxl]
  cxl_remove+0x104/0x210 [cxl]
  pci_device_remove+0x6c/0x110
  device_release_driver_internal+0x204/0x2e0
  pci_stop_bus_device+0xa0/0xd0
  pci_stop_and_remove_bus_device+0x28/0x40
  pci_hp_remove_devices+0xb0/0x150
  pci_hp_remove_devices+0x68/0x150
  eeh_handle_normal_event+0x140/0x580
  eeh_handle_event+0x174/0x360
  eeh_event_handler+0x1e8/0x1f0

This patch fixes the issue of double free_irq by checking that variables that hold the virqs (err_hwirq, serr_hwirq, psl_virq) are not '0' before un-mapping and resetting these variables to '0' when they are un-mapped.

---
 drivers/misc/cxl/native.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

@@ -1066,13 +1066,16 @@ int cxl_native_register_psl_err_irq(stru
 
 void cxl_native_release_psl_err_irq(struct cxl *adapter)
 {
-	if (adapter->native->err_virq != irq_find_mapping(NULL, adapter->native->err_hwirq))
+	if (adapter->native->err_virq == 0 ||
+	    adapter->native->err_virq !=
+	    irq_find_mapping(NULL, adapter->native->err_hwirq))
 		return;
 
 	cxl_p1_write(adapter, CXL_PSL_ErrIVTE, 0x0000000000000000);
 	cxl_unmap_irq(adapter->native->err_virq, adapter);
 	cxl_ops->release_one_irq(adapter, adapter->native->err_hwirq);
 	kfree(adapter->irq_name);
+	adapter->native->err_virq = 0;
 }
 
 int cxl_native_register_serr_irq(struct cxl_afu *afu)

@@ -1102,13 +1105,15 @@ int cxl_native_register_serr_irq(struct
 
 void cxl_native_release_serr_irq(struct cxl_afu *afu)
 {
-	if (afu->serr_virq != irq_find_mapping(NULL, afu->serr_hwirq))
+	if (afu->serr_virq == 0 ||
+	    afu->serr_virq != irq_find_mapping(NULL, afu->serr_hwirq))
 		return;
 
 	cxl_p1n_write(afu, CXL_PSL_SERR_An, 0x0000000000000000);
 	cxl_unmap_irq(afu->serr_virq, afu);
 	cxl_ops->release_one_irq(afu->adapter, afu->serr_hwirq);
 	kfree(afu->err_irq_name);
+	afu->serr_virq = 0;
 }
 
 int cxl_native_register_psl_irq(struct cxl_afu *afu)

@@ -1131,12 +1136,15 @@ int cxl_native_register_psl_irq(struct c
 
 void cxl_native_release_psl_irq(struct cxl_afu *afu)
 {
-	if (afu->native->psl_virq != irq_find_mapping(NULL, afu->native->psl_hwirq))
+	if (afu->native->psl_virq == 0 ||
+	    afu->native->psl_virq !=
+	    irq_find_mapping(NULL, afu->native->psl_hwirq))
 		return;
 
 	cxl_unmap_irq(afu->native->psl_virq, afu);
 	cxl_ops->release_one_irq(afu->adapter, afu->native->psl_hwirq);
 	kfree(afu->psl_irq_name);
+	afu->native->psl_virq = 0;
 }
 
 static void recover_psl_err(struct cxl_afu *afu, u64 errstat)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/cxl-fix-error-path-on-bad-ioctl.patch queue-4.9/cxl-avoid-double-free_irq-for-psl-slice-interrupts.patch