This is a note to let you know that I've just added the patch titled
dmaengine: idxd: Prevent use after free on completion memory
to the 6.1-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:
dmaengine-idxd-prevent-use-after-free-on-completion-memory.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1beeec45f9ac31eba52478379f70a5fa9c2ad005 Mon Sep 17 00:00:00 2001
From: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Date: Wed, 7 Dec 2022 14:52:21 -0800
Subject: dmaengine: idxd: Prevent use after free on completion memory
From: Reinette Chatre <reinette.chatre@xxxxxxxxx>
commit 1beeec45f9ac31eba52478379f70a5fa9c2ad005 upstream.
On driver unload any pending descriptors are flushed at the
time the interrupt is freed:
idxd_dmaengine_drv_remove() ->
drv_disable_wq() ->
idxd_wq_free_irq() ->
idxd_flush_pending_descs().
If there are any descriptors present that need to be flushed this
flow triggers a "not present" page fault as below:
BUG: unable to handle page fault for address: ff391c97c70c9040
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
The address that triggers the fault is the address of the
descriptor that was freed moments earlier via:
drv_disable_wq()->idxd_wq_free_resources()
Fix the use after free by freeing the descriptors after any possible
usage. This is done after idxd_wq_reset() to ensure that the memory
remains accessible during possible completion writes by the device.
Fixes: 63c14ae6c161 ("dmaengine: idxd: refactor wq driver enable/disable operations")
Suggested-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Reviewed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/6c4657d9cff0a0a00501a7b928297ac966e9ec9d.1670452419.git.reinette.chatre@xxxxxxxxx
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/dma/idxd/device.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -1408,11 +1408,11 @@ void drv_disable_wq(struct idxd_wq *wq)
dev_warn(dev, "Clients has claim on wq %d: %d\n",
wq->id, idxd_wq_refcount(wq));
- idxd_wq_free_resources(wq);
idxd_wq_unmap_portal(wq);
idxd_wq_drain(wq);
idxd_wq_free_irq(wq);
idxd_wq_reset(wq);
+ idxd_wq_free_resources(wq);
percpu_ref_exit(&wq->wq_active);
wq->type = IDXD_WQT_NONE;
wq->client_count = 0;
Patches currently in stable-queue which might be from reinette.chatre@xxxxxxxxx are
queue-6.1/dmaengine-idxd-do-not-call-dmx-tx-callbacks-during-workqueue-disable.patch
queue-6.1/dmaengine-idxd-let-probe-fail-when-workqueue-cannot-be-enabled.patch
queue-6.1/dmaengine-idxd-prevent-use-after-free-on-completion-memory.patch
