FAILED: Patch "mfd: core: Add locking around 'mfd_of_node_list'" failed to apply to 6.12-stable tree

PATCH Sasha Levin 2 participants 4 messages Mar 1 – Mar 10

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Stable branch Multifunction devices (MFD)

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Sasha Levin

author maintainer

2026-03-01 01:22 UTC #0 lore raw

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 20117c92bcf9c11afd64d7481d8f94fdf410726e Mon Sep 17 00:00:00 2001
From: Douglas Anderson <[email protected]>
Date: Wed, 10 Dec 2025 11:30:03 -0800
Subject: [PATCH] mfd: core: Add locking around 'mfd_of_node_list'

Manipulating a list in the kernel isn't safe without some sort of mutual exclusion. Add a mutex any time we access / modify 'mfd_of_node_list' to prevent possible crashes.

Cc [email protected]

Fixes 466a62d7642f ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")

Signed-off-by Douglas Anderson <[email protected]>

Link https://patch.msgid.link/20251210113002.1.I6ceaca2cfb7eb25737012b166671f516696be4fd@changeid open here

Signed-off-by Lee Jones <[email protected]>

---
 drivers/mfd/mfd-core.c | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

drivers/mfd/mfd-core.c +22 ~~-14~~

index 6925bedddc80b..a30f93bf030aa 100644
@@ -22,6 +22,7 @@
 #include <linux/regulator/consumer.h>
 
 static LIST_HEAD(mfd_of_node_list);
+static DEFINE_MUTEX(mfd_of_node_mutex);
 
 struct mfd_of_node_entry {
 	struct list_head list;

@@ -104,9 +105,11 @@ static int mfd_match_of_node_to_dev(struct platform_device *pdev,
 	u64 of_node_addr;
 
 	/* Skip if OF node has previously been allocated to a device */
-	list_for_each_entry(of_entry, &mfd_of_node_list, list)
-		if (of_entry->np == np)
-			return -EAGAIN;
+	scoped_guard(mutex, &mfd_of_node_mutex) {
+		list_for_each_entry(of_entry, &mfd_of_node_list, list)
+			if (of_entry->np == np)
+				return -EAGAIN;
+	}
 
 	if (!cell->use_of_reg)
 		/* No of_reg defined - allocate first free compatible match */

@@ -128,7 +131,8 @@ static int mfd_match_of_node_to_dev(struct platform_device *pdev,
 
 	of_entry->dev = &pdev->dev;
 	of_entry->np = np;
-	list_add_tail(&of_entry->list, &mfd_of_node_list);
+	scoped_guard(mutex, &mfd_of_node_mutex)
+		list_add_tail(&of_entry->list, &mfd_of_node_list);
 
 	of_node_get(np);
 	device_set_node(&pdev->dev, of_fwnode_handle(np));

@@ -284,11 +288,13 @@ static int mfd_add_device(struct device *parent, int id,
 	if (cell->swnode)
 		device_remove_software_node(&pdev->dev);
 fail_of_entry:
-	list_for_each_entry_safe(of_entry, tmp, &mfd_of_node_list, list)
-		if (of_entry->dev == &pdev->dev) {
-			list_del(&of_entry->list);
-			kfree(of_entry);
-		}
+	scoped_guard(mutex, &mfd_of_node_mutex) {
+		list_for_each_entry_safe(of_entry, tmp, &mfd_of_node_list, list)
+			if (of_entry->dev == &pdev->dev) {
+				list_del(&of_entry->list);
+				kfree(of_entry);
+			}
+	}
 fail_alias:
 	regulator_bulk_unregister_supply_alias(&pdev->dev,
 					       cell->parent_supplies,

@@ -358,11 +364,13 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
 	if (cell->swnode)
 		device_remove_software_node(&pdev->dev);
 
-	list_for_each_entry_safe(of_entry, tmp, &mfd_of_node_list, list)
-		if (of_entry->dev == &pdev->dev) {
-			list_del(&of_entry->list);
-			kfree(of_entry);
-		}
+	scoped_guard(mutex, &mfd_of_node_mutex) {
+		list_for_each_entry_safe(of_entry, tmp, &mfd_of_node_list, list)
+			if (of_entry->dev == &pdev->dev) {
+				list_del(&of_entry->list);
+				kfree(of_entry);
+			}
+	}
 
 	regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
 					       cell->num_parent_supplies);

Signature · 1 line

2.51.0

Doug Anderson

2026-03-02 03:01 UTC #1 lore raw

Sasha,

Quoted 9 lines · Sasha Levin

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
Thanks,
Sasha

Quoted 6 lines

------------------ original commit in Linus's tree ------------------
From 20117c92bcf9c11afd64d7481d8f94fdf410726e Mon Sep 17 00:00:00 2001
From: Douglas Anderson <[email protected]>
Date: Wed, 10 Dec 2025 11:30:03 -0800
Subject: [PATCH] mfd: core: Add locking around 'mfd_of_node_list'

Can you give any more details? I tried:

git checkout v6.12.74
git cherry-pick 20117c92bcf9 # ("mfd: core: Add locking around 'mfd_of_node_list'")

It seems to apply all the way back to 6.1 cleanly. NOTE: I didn't try building with those older kernels. I can try if need be.

-Doug

Doug Anderson

2026-03-09 22:50 UTC #2 lore raw

Hi,

Quoted 22 lines · Doug Anderson

Sasha,
Quoted 9 lines · Sasha Levin
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
Thanks,
Sasha
Quoted 6 lines
------------------ original commit in Linus's tree ------------------
From 20117c92bcf9c11afd64d7481d8f94fdf410726e Mon Sep 17 00:00:00 2001
From: Douglas Anderson <[email protected]>
Date: Wed, 10 Dec 2025 11:30:03 -0800
Subject: [PATCH] mfd: core: Add locking around 'mfd_of_node_list'
Can you give any more details? I tried:

Quoted 8 lines

git checkout v6.12.74
git cherry-pick 20117c92bcf9 # ("mfd: core: Add locking around 'mfd_of_node_list'")
It seems to apply all the way back to 6.1 cleanly. NOTE: I didn't try building with those older kernels. I can try if need be.
-Doug

FWIW, I checked and v6.12.76 has the patch. So does the top of the 6.6 and 6.1 stable trees. So I guess this was a false positive report? ...or maybe you tried to apply it twice?

If someone wants this on 5.15, I think it's as easy as picking up commit 8e88c61d6f34 ("mfd: core: Delete corresponding OF node entries from list on MFD removal") as a stable dep.

If someone wants this on 5.10, we might need some extra backporting... If someone is truly interested, let me know.

-Doug

Sasha Levin

author maintainer

2026-03-10 09:52 UTC #3 lore raw

Quoted 29 lines · Doug Anderson

Hi,
Quoted 26 lines · Doug Anderson
Sasha,
Quoted 9 lines · Sasha Levin
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
Thanks,
Sasha
Quoted 6 lines
------------------ original commit in Linus's tree ------------------
From 20117c92bcf9c11afd64d7481d8f94fdf410726e Mon Sep 17 00:00:00 2001
From: Douglas Anderson <[email protected]>
Date: Wed, 10 Dec 2025 11:30:03 -0800
Subject: [PATCH] mfd: core: Add locking around 'mfd_of_node_list'
Can you give any more details? I tried:
git checkout v6.12.74
git cherry-pick 20117c92bcf9 # ("mfd: core: Add locking around 'mfd_of_node_list'")

Quoted 8 lines

Quoted 4 lines
It seems to apply all the way back to 6.1 cleanly. NOTE: I didn't try building with those older kernels. I can try if need be.
-Doug
FWIW, I checked and v6.12.76 has the patch. So does the top of the 6.6 and 6.1 stable trees. So I guess this was a false positive report? ...or maybe you tried to apply it twice?

Nope, it was an issue with scripts on my end. Nothing needed for those trees :)

Signature · 2 lines

Thanks,
Sasha