[PATCH 6.6.y 2/2] most: core: fix leak on early registration failure

[Artem Dinaburg <artem@trailofbits.com>]

From: Johan Hovold <johan@kernel.org>

[ Upstream commit 2c198c272f9c9213b0fdf6b4a879f445c574f416 ]

A recent commit fixed a resource leak on early registration failures but
for some reason left out the first error path which still leaks the
resources associated with the interface.

Fix up also the first error path so that the interface is always
released on errors.

Fixes: 1f4c9d8a1021 ("most: core: fix resource leak in most_register_interface error paths")
Fixes: 723de0f9171e ("staging: most: remove device from interface structure")
Cc: Christian Gromm <christian.gromm@microchip.com>
Cc: Navaneeth K <knavaneeth786@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20260116162950.21578-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
---
Hi,

Please consider this backport of the fix for CVE-2026-43317 to 6.6.y.

The code changes are identical to upstream.

The complete fix is already present in 6.12.y, 6.18.y and 7.2.y.

Build-tested only as part of a cumulative 6.6.y series: x86_64 objects
(allmodconfig, CONFIG_WERROR=y); no runtime testing.

Thanks,
Artem Dinaburg

 drivers/most/core.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/most/core.c b/drivers/most/core.c
index 0fbf06d34e0b968e6444877af981322a3793d406..3d1102faec8a2f37b1c4abcb99236db39b79094e 100644
--- a/drivers/most/core.c
+++ b/drivers/most/core.c
@@ -1282,12 +1282,17 @@ int most_register_interface(struct most_interface *iface)
 	int id;
 	struct most_channel *c;
 
-	if (!iface || !iface->enqueue || !iface->configure ||
-	    !iface->poison_channel || (iface->num_channels > MAX_CHANNELS))
+	if (!iface)
 		return -EINVAL;
 
 	device_initialize(iface->dev);
 
+	if (!iface->enqueue || !iface->configure || !iface->poison_channel ||
+	    (iface->num_channels > MAX_CHANNELS)) {
+		put_device(iface->dev);
+		return -EINVAL;
+	}
+
 	id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
 	if (id < 0) {
 		dev_err(iface->dev, "Failed to allocate device ID\n");