Patch "scsi: aacraid: Prevent crash in case of free interrupt during scsi EH path" has been added to the 4.14-stable tree

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

scsi: aacraid: Prevent crash in case of free interrupt during scsi EH path

to the 4.14-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:
scsi-aacraid-prevent-crash-in-case-of-free-interrupt-during-scsi-eh-path.patch
and it can be found in the queue-4.14 subdirectory.

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

From: "Guilherme G. Piccoli" <[email protected]>
Date: Fri, 17 Nov 2017 19:14:55 -0200
Subject: scsi: aacraid: Prevent crash in case of free interrupt during scsi EH path

From: "Guilherme G. Piccoli" <[email protected]>

[ Upstream commit e4717292ddebcfe231651b5aff9fa19ca158d178 ]

As part of the scsi EH path, aacraid performs a reinitialization of the adapter, which encompass freeing resources and IRQs, NULLifying lots of pointers, and then initialize it all over again. We've identified a problem during the free IRQ portion of this path if CONFIG_DEBUG_SHIRQ is enabled on kernel config file.

Happens that, in case this flag was set, right after free_irq() effectively clears the interrupt, it checks if it was requested as IRQF_SHARED. In positive case, it performs another call to the IRQ handler on driver. Problem is: since aacraid currently free some resources *before* freeing the IRQ, once free_irq() path calls the handler again (due to CONFIG_DEBUG_SHIRQ), aacraid crashes due to NULL pointer dereference with the following trace:

  aac_src_intr_message+0xf8/0x740 [aacraid]
  __free_irq+0x33c/0x4a0
  free_irq+0x78/0xb0
  aac_free_irq+0x13c/0x150 [aacraid]
  aac_reset_adapter+0x2e8/0x970 [aacraid]
  aac_eh_reset+0x3a8/0x5d0 [aacraid]
  scsi_try_host_reset+0x74/0x180
  scsi_eh_ready_devs+0xc70/0x1510
  scsi_error_handler+0x624/0xa20

This patch prevents the crash by changing the order of the deinitialization in this path of aacraid: first we clear the IRQ, then we free other resources. No functional change intended.

---
 drivers/scsi/aacraid/commsup.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -1583,6 +1583,7 @@ static int _aac_reset_adapter(struct aac
 	 * will ensure that i/o is queisced and the card is flushed in that
 	 * case.
 	 */
+	aac_free_irq(aac);
 	aac_fib_map_free(aac);
 	dma_free_coherent(&aac->pdev->dev, aac->comm_size, aac->comm_addr,
 			  aac->comm_phys);

@@ -1590,7 +1591,6 @@ static int _aac_reset_adapter(struct aac
 	aac->comm_phys = 0;
 	kfree(aac->queues);
 	aac->queues = NULL;
-	aac_free_irq(aac);
 	kfree(aac->fsa_dev);
 	aac->fsa_dev = NULL;
 

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

queue-4.14/scsi-aacraid-prevent-crash-in-case-of-free-interrupt-during-scsi-eh-path.patch queue-4.14/scsi-aacraid-fix-hang-in-kdump.patch