FAILED: patch "[PATCH] hwmon: (coretemp) Set nr_cores only after core_data allocation succeeds" failed to apply to 6.12-stable tree

[Sasha Levin <sashal@kernel.org>]

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 <stable@vger.kernel.org>.

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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 95638f1f05ced75a82e83f610cd01b636d2a21b1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261109200726-failed-6.12-95638f1f05ce@kernel.org' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Thanks,
Sasha

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

From 95638f1f05ced75a82e83f610cd01b636d2a21b1 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Sat, 31 Oct 2026 03:08:32 +0000
Subject: [PATCH] hwmon: (coretemp) Set nr_cores only after core_data
 allocation succeeds
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

In init_temp_data(), pdata->nr_cores is populated from
topology_num_cores_per_package() before allocating pdata->core_data. If
that allocation fails, init_temp_data() returns NULL with
pdata->core_data still NULL and pdata->nr_cores set to a positive value.

coretemp_add_core() logs the error without failing coretemp_cpu_online(),
so the CPU still comes online with pdata->hwmon_dev registered. When the
CPU is later taken offline (or the module is unloaded),
coretemp_cpu_offline() calls get_temp_data(pd, cpu), which loops up to
pdata->nr_cores and dereferences the NULL pdata->core_data pointer.

Store the core count in a local variable and assign pdata->nr_cores only
after pdata->core_data is allocated, preserving the invariant that
pdata->nr_cores is zero whenever pdata->core_data is NULL.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Fixes: 1a793caf6f69 ("hwmon: (coretemp) Use dynamic allocated memory for core temp_data")
Cc: stable@vger.kernel.org
Tested-by: Asaf Nuri Bertizlioğlu <ycistak@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/coretemp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index eb74ecd12310a..7fced0e2abeba 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -491,11 +491,12 @@ init_temp_data(struct platform_data *pdata, unsigned int cpu, int pkg_flag)
 	struct temp_data *tdata;
 
 	if (!pdata->core_data) {
-		pdata->nr_cores = topology_num_cores_per_package();
-		pdata->core_data = kzalloc_objs(struct temp_data *,
-						pdata->nr_cores);
+		int nr_cores = topology_num_cores_per_package();
+
+		pdata->core_data = kzalloc_objs(struct temp_data *, nr_cores);
 		if (!pdata->core_data)
 			return NULL;
+		pdata->nr_cores = nr_cores;
 	}
 
 	tdata = kzalloc_obj(struct temp_data);
-- 
2.53.0