From: Lukas Wunner lukas@wunner.de
commit 7174dc655ef0578877b0b4598e69619d2be28b4d upstream.
If the call to devm_spi_register_master() fails on probe of the GPIO SPI driver, the spi_master struct is erroneously not freed:
After allocating the spi_master, its reference count is 1. The driver unconditionally decrements the reference count on unbind using a devm action. Before calling devm_spi_register_master(), the driver unconditionally increments the reference count because on success, that function will decrement the reference count on unbind. However on failure, devm_spi_register_master() does *not* decrement the reference count, so the spi_master is leaked.
The issue was introduced by commits 8b797490b4db ("spi: gpio: Make sure spi_master_put() is called in every error path") and 79567c1a321e ("spi: gpio: Use devm_spi_register_master()"), which sought to plug leaks introduced by 9b00bc7b901f ("spi: spi-gpio: Rewrite to use GPIO descriptors") but missed this remaining leak.
The situation was later aggravated by commit d3b0ffa1d75d ("spi: gpio: prevent memory leak in spi_gpio_probe"), which introduced a use-after-free because it releases a reference on the spi_master if devm_add_action_or_reset() fails even though the function already does that.
Fix by switching over to the new devm_spi_alloc_master() helper.
Fixes: 9b00bc7b901f ("spi: spi-gpio: Rewrite to use GPIO descriptors") Signed-off-by: Lukas Wunner lukas@wunner.de Reviewed-by: Linus Walleij linus.walleij@linaro.org Cc: stable@vger.kernel.org # v4.17+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation Cc: stable@vger.kernel.org # v5.1-: 8b797490b4db: spi: gpio: Make sure spi_master_put() is called in every error path Cc: stable@vger.kernel.org # v5.1-: 45beec351998: spi: bitbang: Introduce spi_bitbang_init() Cc: stable@vger.kernel.org # v5.1-: 79567c1a321e: spi: gpio: Use devm_spi_register_master() Cc: stable@vger.kernel.org # v5.4-: d3b0ffa1d75d: spi: gpio: prevent memory leak in spi_gpio_probe Cc: stable@vger.kernel.org # v4.17+ Cc: Navid Emamdoost navid.emamdoost@gmail.com Cc: Andrey Smirnov andrew.smirnov@gmail.com Link: https://lore.kernel.org/r/86eaed27431c3d709e3748eb76ceecbfc790dd37.160728688... Signed-off-by: Mark Brown broonie@kernel.org [lukas: backport to v4.19.192] Signed-off-by: Lukas Wunner lukas@wunner.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/spi/spi-gpio.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
--- a/drivers/spi/spi-gpio.c +++ b/drivers/spi/spi-gpio.c @@ -382,7 +382,7 @@ static int spi_gpio_probe(struct platfor return -ENODEV; #endif
- master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio)); + master = devm_spi_alloc_master(&pdev->dev, sizeof(*spi_gpio)); if (!master) return -ENOMEM;
@@ -438,11 +438,7 @@ static int spi_gpio_probe(struct platfor } spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
- status = spi_bitbang_start(&spi_gpio->bitbang); - if (status) - spi_master_put(master); - - return status; + return spi_bitbang_start(&spi_gpio->bitbang); }
static int spi_gpio_remove(struct platform_device *pdev)