FAILED: patch "[PATCH] Bluetooth: mgmt: fix race in read_unconf_index_list()" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-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]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x b5dbb41b212c50c095a4dbee3017a84fe94f033b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092918-appraisal-strive-14ac@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From b5dbb41b212c50c095a4dbee3017a84fe94f033b Mon Sep 17 00:00:00 2001
From: Aldo Ariel Panzardo <[email protected]>
Date: Tue, 15 Sep 2026 12:59:52 -0300
Subject: [PATCH] Bluetooth: mgmt: fix race in read_unconf_index_list()

read_unconf_index_list() counts unconfigured controllers before allocating its response, then checks the device flags again while filling it.

hci_dev_list_lock stabilizes list membership, but it does not serialize the per-device flags. During asynchronous controller setup, the worker can set HCI_UNCONFIGURED and clear HCI_SETUP between the two passes. A controller omitted from the allocation count can then become eligible for the fill pass, causing an out-of-bounds write to rp->index[].

Allocate space for every device on hci_dev_list. Since list membership cannot change while hci_dev_list_lock is held, the response remains large enough regardless of flag transitions. The reported count and response length still include only eligible unconfigured controllers.

index f740e745ae78..41956cdde982 100644
@@ -496,13 +496,9 @@ static int read_unconf_index_list(struct sock *sk, struct hci_dev *hdev,
 
 	read_lock(&hci_dev_list_lock);
 
-	count = 0;
-	list_for_each_entry(d, &hci_dev_list, list) {
-		if (hci_dev_test_flag(d, HCI_UNCONFIGURED))
-			count++;
-	}
+	count = list_count_nodes(&hci_dev_list);
 
-	rp_len = sizeof(*rp) + (2 * count);
+	rp_len = sizeof(*rp) + (sizeof(__le16) * count);
 	rp = kmalloc(rp_len, GFP_ATOMIC);
 	if (!rp) {
 		read_unlock(&hci_dev_list_lock);

From: Aldo Ariel Panzardo <[email protected]>

[ Upstream commit b5dbb41b212c50c095a4dbee3017a84fe94f033b ]

read_unconf_index_list() counts unconfigured controllers before allocating its response, then checks the device flags again while filling it.

hci_dev_list_lock stabilizes list membership, but it does not serialize the per-device flags. During asynchronous controller setup, the worker can set HCI_UNCONFIGURED and clear HCI_SETUP between the two passes. A controller omitted from the allocation count can then become eligible for the fill pass, causing an out-of-bounds write to rp->index[].

Allocate space for every device on hci_dev_list. Since list membership cannot change while hci_dev_list_lock is held, the response remains large enough regardless of flag transitions. The reported count and response length still include only eligible unconfigured controllers.

---
 net/bluetooth/mgmt.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

index c53b128adb7bd..6173247dd45d7 100644
@@ -500,12 +500,10 @@ static int read_unconf_index_list(struct sock *sk, struct hci_dev *hdev,
 	read_lock(&hci_dev_list_lock);
 
 	count = 0;
-	list_for_each_entry(d, &hci_dev_list, list) {
-		if (hci_dev_test_flag(d, HCI_UNCONFIGURED))
-			count++;
-	}
+	list_for_each_entry(d, &hci_dev_list, list)
+		count++;
 
-	rp_len = sizeof(*rp) + (2 * count);
+	rp_len = sizeof(*rp) + (sizeof(__le16) * count);
 	rp = kmalloc(rp_len, GFP_ATOMIC);
 	if (!rp) {
 		read_unlock(&hci_dev_list_lock);

2.53.0