On Mon, Dec 28, 2020 at 11:50:02AM +0100, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 4.4-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.

Here's the backport of e77df3eca12b to v4.4-stable.

-- >8 -- From: Lukas Wunner lukas@wunner.de Date: Mon, 7 Dec 2020 09:17:04 +0100 Subject: [PATCH] spi: spi-sh: Fix use-after-free on unbind

commit e77df3eca12be4b17f13cf9f215cff248c57d98f upstream.

spi_sh_remove() accesses the driver's private data after calling spi_unregister_master() even though that function releases the last reference on the spi_master and thereby frees the private data.

Fix by switching over to the new devm_spi_alloc_master() helper which keeps the private data accessible until the driver has unbound.

Fixes: 680c1305e259 ("spi/spi_sh: use spi_unregister_master instead of spi_master_put in remove path") Signed-off-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v3.0+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation Cc: stable@vger.kernel.org # v3.0+ Cc: Axel Lin axel.lin@ingics.com Link: https://lore.kernel.org/r/6d97628b536baf01d5e3e39db61108f84d44c8b2.160728688... Signed-off-by: Mark Brown broonie@kernel.org [lukas: backport to v4.4.270] Signed-off-by: Lukas Wunner lukas@wunner.de --- drivers/spi/spi-sh.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-sh.c b/drivers/spi/spi-sh.c index 502501187c9e..f062ebb46e0e 100644 --- a/drivers/spi/spi-sh.c +++ b/drivers/spi/spi-sh.c @@ -451,7 +451,7 @@ static int spi_sh_probe(struct platform_device *pdev) return -ENODEV; }

- master = spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data)); + master = devm_spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data)); if (master == NULL) { dev_err(&pdev->dev, "spi_alloc_master error.\n"); return -ENOMEM; @@ -469,16 +469,14 @@ static int spi_sh_probe(struct platform_device *pdev) break; default: dev_err(&pdev->dev, "No support width\n"); - ret = -ENODEV; - goto error1; + return -ENODEV; } ss->irq = irq; ss->master = master; ss->addr = devm_ioremap(&pdev->dev, res->start, resource_size(res)); if (ss->addr == NULL) { dev_err(&pdev->dev, "ioremap error.\n"); - ret = -ENOMEM; - goto error1; + return -ENOMEM; } INIT_LIST_HEAD(&ss->queue); spin_lock_init(&ss->lock); @@ -488,8 +486,7 @@ static int spi_sh_probe(struct platform_device *pdev) dev_name(master->dev.parent)); if (ss->workqueue == NULL) { dev_err(&pdev->dev, "create workqueue error\n"); - ret = -EBUSY; - goto error1; + return -EBUSY; }

ret = request_irq(irq, spi_sh_irq, 0, "spi_sh", ss); @@ -516,9 +513,6 @@ static int spi_sh_probe(struct platform_device *pdev) free_irq(irq, ss); error2: destroy_workqueue(ss->workqueue); - error1: - spi_master_put(master); - return ret; }