Re: [PATCH 1/5] i2c: mpc: fix device_node refcount leak in fsl_i2c_probe()/fsl_i2c_remove()
From: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Date: 2026-08-16 21:49:50
Also in:
linux-arm-kernel, linux-i2c, lkml, stable
Hi Liu On 16/08/2026 06:12, Liu Zhenlong wrote:
fsl_i2c_probe() calls of_node_get() to take an extra reference on the
platform device's of_node when assigning it to the adapter device, but
neither the probe error path nor fsl_i2c_remove() drops it.
device_release() does not call of_node_put() and i2c_adapter_dev_release()
only completes a struct, so the extra reference is never released, leaking
the device_node on every probe failure and every adapter removal.
Add the matching of_node_put() to both paths.
In the probe error path, i2c_add_numbered_adapter() failure does not run
i2c_del_adapter(), so of_node_put(i2c->adap.dev.of_node) is safe.
In fsl_i2c_remove(), i2c_del_adapter() clears adap->dev with memset() at
the end (commit bd4bc3dbded9 ("i2c: Clear i2c_adapter.dev on adapter
removal")), which zeroes adap->dev.of_node before of_node_put() runs,
turning it into a no-op. Cache the pointer before calling
i2c_del_adapter(), the same approach used in i2c-mux
(i2c_mux_del_adapters) and mtd (commit 56570bdad5e3 ("mtd: core: Fix
refcount error in del_mtd_device()")).
Compile-tested with gcc-powerpc-linux-gnu on pmac32 defconfig; no
hardware available for runtime testing.
Fixes: 9fd049927ccb ("of/i2c: Generalize OF support")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Liu Zhenlong <redacted>I did wonder if there was a better way of fixing this generically since it affects multiple drivers e.g. doing the put in i2c_del_adapter(), adding a devm_ function than deals with the reference or just not acquiring the reference (which seems to be what SPI does). Regardless for an older driver like i2c-mpc this is probably a minimally sane fix. Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
quoted hunk ↗ jump to hunk
--- drivers/i2c/busses/i2c-mpc.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index a21fa45bd64c..8182f7dc3d0f 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c@@ -867,8 +867,10 @@ static int fsl_i2c_probe(struct platform_device *op) i2c_set_adapdata(&i2c->adap, i2c); result = i2c_add_numbered_adapter(&i2c->adap); - if (result) + if (result) { + of_node_put(i2c->adap.dev.of_node); return result; + } return 0; };@@ -876,8 +878,10 @@ static int fsl_i2c_probe(struct platform_device *op) static void fsl_i2c_remove(struct platform_device *op) { struct mpc_i2c *i2c = platform_get_drvdata(op); + struct device_node *node = i2c->adap.dev.of_node; i2c_del_adapter(&i2c->adap); + of_node_put(node); }; static int __maybe_unused mpc_i2c_suspend(struct device *dev)