2021-06-11 10:23:19

by Takashi Iwai

Subject: [PATCH v2] mmc: sdhci: Clear unused bounce buffer at DMA mmap error path

When DMA-mapping of the bounce buffer fails, the driver tries to fall
back, but it leaves the allocated host->bounce_buffer although its
size is zero. Later on, the driver checks the use of bounce buffer
with host->bounce_buffer pointer, and it tries to use the buffer
incorrectly, resulting in Oops.

This patch clears the release the unused buffer and clears the
bounce_buffer pointer for addressing the problem.

Acked-by: Adrian Hunter <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
---
v1->v2: correct the device pointer to mmc_dev(mmc)

drivers/mmc/host/sdhci.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index bf238ade1602..c80bc6c4ebf3 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -4072,9 +4072,13 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host)
bounce_size,
DMA_BIDIRECTIONAL);
ret = dma_mapping_error(mmc_dev(mmc), host->bounce_addr);
- if (ret)
+ if (ret) {
+ devm_kfree(mmc_dev(mmc), host->bounce_buffer);
+ host->bounce_buffer = NULL;
/* Again fall back to max_segs == 1 */
return;
+ }
+
host->bounce_buffer_size = bounce_size;

/* Lie about this since we're bouncing */
--
2.26.2

2021-06-29 15:11:12

by Ulf Hansson

Subject: Re: [PATCH v2] mmc: sdhci: Clear unused bounce buffer at DMA mmap error path

On Fri, 11 Jun 2021 at 12:19, Takashi Iwai <[email protected]> wrote:
>
> When DMA-mapping of the bounce buffer fails, the driver tries to fall
> back, but it leaves the allocated host->bounce_buffer although its
> size is zero. Later on, the driver checks the use of bounce buffer
> with host->bounce_buffer pointer, and it tries to use the buffer
> incorrectly, resulting in Oops.
>
> This patch clears the release the unused buffer and clears the
> bounce_buffer pointer for addressing the problem.
>
> Acked-by: Adrian Hunter <[email protected]>
> Signed-off-by: Takashi Iwai <[email protected]>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
> v1->v2: correct the device pointer to mmc_dev(mmc)
>
> drivers/mmc/host/sdhci.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index bf238ade1602..c80bc6c4ebf3 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -4072,9 +4072,13 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host)
> bounce_size,
> DMA_BIDIRECTIONAL);
> ret = dma_mapping_error(mmc_dev(mmc), host->bounce_addr);
> - if (ret)
> + if (ret) {
> + devm_kfree(mmc_dev(mmc), host->bounce_buffer);
> + host->bounce_buffer = NULL;
> /* Again fall back to max_segs == 1 */
> return;
> + }
> +
> host->bounce_buffer_size = bounce_size;
>
> /* Lie about this since we're bouncing */
> --
> 2.26.2
>