FAILED: patch "[PATCH] Bluetooth: MGMT: validate Add Extended Advertising Data" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x d3f7d17960ed50df3a6709c5158caff989c8c905
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026052818-tattered-watch-83b6@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From d3f7d17960ed50df3a6709c5158caff989c8c905 Mon Sep 17 00:00:00 2001
From: Michael Bommarito <[email protected]>
Date: Fri, 15 May 2026 10:38:19 -0400
Subject: [PATCH] Bluetooth: MGMT: validate Add Extended Advertising Data
length

MGMT_OP_ADD_EXT_ADV_DATA is registered as a variable-length command, with MGMT_ADD_EXT_ADV_DATA_SIZE as the fixed header size. The handler then uses cp->adv_data_len and cp->scan_rsp_len to validate and copy cp->data, but it never checks that those bytes are part of the mgmt command payload.

A short command can therefore make add_ext_adv_data() pass an out-of-bounds pointer into tlv_data_is_valid(). If the bytes beyond the command buffer are addressable, they can also be copied into the advertising instance as scan response data, where the caller can read them back via MGMT_OP_GET_ADV_INSTANCE. The trigger requires CAP_NET_ADMIN in the initial user namespace; KASAN reports an 8-byte slab-out-of-bounds read.

Reject commands whose length does not match the fixed header plus both advertising data lengths before parsing cp->data.

index b05bb380e5f8..de5bd6b637b2 100644
@@ -9110,9 +9110,15 @@ static int add_ext_adv_data(struct sock *sk, struct hci_dev *hdev, void *data,
 	struct adv_info *adv_instance;
 	int err = 0;
 	struct mgmt_pending_cmd *cmd;
+	u16 expected_len;
 
 	BT_DBG("%s", hdev->name);
 
+	expected_len = struct_size(cp, data, cp->adv_data_len + cp->scan_rsp_len);
+	if (expected_len != data_len)
+		return mgmt_cmd_status(sk, hdev->id, MGMT_OP_ADD_EXT_ADV_DATA,
+				       MGMT_STATUS_INVALID_PARAMS);
+
 	hci_dev_lock(hdev);
 
 	adv_instance = hci_find_adv_instance(hdev, cp->instance);