spi: offload: fix use after free

Fix a use after free bug in devm_spi_offload_get() where a pointer
was dereferenced after being freed. Instead, add a new local variable
to avoid needing to use the resource pointer to access the offload
pointer.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202502112344.7ggtFzyn-lkp@intel.com/
Fixes: 5a19e1985d01 ("spi: axi-spi-engine: implement offload support")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250212-spi-offload-fixes-v1-2-e192c69e3bb3@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-offload.c b/drivers/spi/spi-offload.c
index df5e963d5ee29d37833559595536a460c530bc81..6bad042fe4373e8b91dae3154ef5e22744a4acd0 100644 (file)
--- a/drivers/spi/spi-offload.c
+++ b/drivers/spi/spi-offload.c
@@ -108,6 +108,7 @@ struct spi_offload *devm_spi_offload_get(struct device *dev,
                                         const struct spi_offload_config *config)
 {
        struct spi_controller_and_offload *resource;
+       struct spi_offload *offload;
        int ret;
 
        if (!spi || !config)
@@ -120,18 +121,20 @@ struct spi_offload *devm_spi_offload_get(struct device *dev,
        if (!resource)
                return ERR_PTR(-ENOMEM);
 
-       resource->controller = spi->controller;
-       resource->offload = spi->controller->get_offload(spi, config);
-       if (IS_ERR(resource->offload)) {
+       offload = spi->controller->get_offload(spi, config);
+       if (IS_ERR(offload)) {
                kfree(resource);
-               return resource->offload;
+               return offload;
        }
 
+       resource->controller = spi->controller;
+       resource->offload = offload;
+
        ret = devm_add_action_or_reset(dev, spi_offload_put, resource);
        if (ret)
                return ERR_PTR(ret);
 
-       return resource->offload;
+       return offload;
 }
 EXPORT_SYMBOL_GPL(devm_spi_offload_get);