2019-01-10 22:34:39

by Remi Pommarel

Subject: [PATCH] mmc: meson-gx: Free irq in release() callback

Because the irq was requested through device managed resources API
(devm_request_threaded_irq()) it was freed after meson_mmc_remove()
completion, thus after mmc_free_host() has reclaimed meson_host memory.
As this irq is IRQF_SHARED, while using CONFIG_DEBUG_SHIRQ, its handler
get called by free_irq(). So meson_mmc_irq() was called after the
meson_host memory reclamation and was using invalid memory.

We ended up with the following scenario:
device_release_driver()
meson_mmc_remove()
mmc_free_host() /* Freeing host memory */
...
devres_release_all()
devm_irq_release()
__free_irq()
meson_mmc_irq() /* Uses freed memory */

To avoid this, the irq is released in meson_mmc_remove() before
mmc_free_host() gets called.

This fixes https://marc.info/?l=linux-mmc&m=154707415208716.

Signed-off-by: Remi Pommarel <[email protected]>
---
drivers/mmc/host/meson-gx-mmc.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index c2690c1a50ff..412cfd16bf15 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -179,6 +179,8 @@ struct meson_host {
struct sd_emmc_desc *descs;
dma_addr_t descs_dma_addr;

+ int irq;
+
bool vqmmc_enabled;
};

@@ -1231,7 +1233,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
struct resource *res;
struct meson_host *host;
struct mmc_host *mmc;
- int ret, irq;
+ int ret;

mmc = mmc_alloc_host(sizeof(struct meson_host), &pdev->dev);
if (!mmc)
@@ -1276,8 +1278,8 @@ static int meson_mmc_probe(struct platform_device *pdev)
goto free_host;
}

- irq = platform_get_irq(pdev, 0);
- if (irq <= 0) {
+ host->irq = platform_get_irq(pdev, 0);
+ if (host->irq <= 0) {
dev_err(&pdev->dev, "failed to get interrupt resource.\n");
ret = -EINVAL;
goto free_host;
@@ -1331,9 +1333,8 @@ static int meson_mmc_probe(struct platform_device *pdev)
writel(IRQ_CRC_ERR | IRQ_TIMEOUTS | IRQ_END_OF_CHAIN,
host->regs + SD_EMMC_IRQ_EN);

- ret = devm_request_threaded_irq(&pdev->dev, irq, meson_mmc_irq,
- meson_mmc_irq_thread, IRQF_SHARED,
- NULL, host);
+ ret = devm_request_threaded_irq(&pdev->dev, host->irq, meson_mmc_irq,
+ meson_mmc_irq_thread, IRQF_SHARED, NULL, host);
if (ret)
goto err_init_clk;

@@ -1387,6 +1388,7 @@ static int meson_mmc_remove(struct platform_device *pdev)

/* disable interrupts */
writel(0, host->regs + SD_EMMC_IRQ_EN);
+ devm_free_irq(host->dev, host->irq, host);

dma_free_coherent(host->dev, SD_EMMC_DESC_BUF_LEN,
host->descs, host->descs_dma_addr);
--
2.20.1

2019-01-11 00:27:25

by Remi Pommarel

Subject: Re: [PATCH] mmc: meson-gx: Free irq in release() callback

On Thu, Jan 10, 2019 at 07:49:08PM +0100, Remi Pommarel wrote:
> Because the irq was requested through device managed resources API
> (devm_request_threaded_irq()) it was freed after meson_mmc_remove()
> completion, thus after mmc_free_host() has reclaimed meson_host memory.
> As this irq is IRQF_SHARED, while using CONFIG_DEBUG_SHIRQ, its handler
> get called by free_irq(). So meson_mmc_irq() was called after the
> meson_host memory reclamation and was using invalid memory.
>
> We ended up with the following scenario:
> device_release_driver()
> meson_mmc_remove()
> mmc_free_host() /* Freeing host memory */
> ...
> devres_release_all()
> devm_irq_release()
> __free_irq()
> meson_mmc_irq() /* Uses freed memory */
>
> To avoid this, the irq is released in meson_mmc_remove() before
> mmc_free_host() gets called.
>

Oups, I missed the fact that the same can happen if probe() callback
fails after allocating the irq.

I will send a V2 for that.

--
Remi