nvmem: mxs-ocotp read problem

nvmem: mxs-ocotp read problem

[Stanislav Meduna]

Hi,

the mxs_ocotp_read seems to incorrectly iterate through
the memory to be read, resulting in a buffer overflow/off-area
access and sometimes oops. The following patch seems to fix
the problem

Regards
                               Stano


diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
index 8ba19bb..914a4fa 100644
--- a/drivers/nvmem/mxs-ocotp.c
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -94,7 +94,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
        if (ret)
                goto close_banks;

-       while (val_size) {
+       while (val_size >= reg_size) {
                if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
                        /* fill up non-data register */
                        *buf = 0;
@@ -103,7 +103,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
                }

                buf++;
-               val_size--;
+               val_size -= reg_size;
                offset += reg_size;
        }

nvmem: mxs-ocotp read problem

[Stefan Wahren]

Hi Stano,

Am 26.04.2016 um 13:45 schrieb Stanislav Meduna:
> Hi,
>
> the mxs_ocotp_read seems to incorrectly iterate through
> the memory to be read, resulting in a buffer overflow/off-area
> access and sometimes oops. 

could you please provide me scenario, so i can test it.

Regards
Stefan

> The following patch seems to fix
> the problem
>
> Regards
>                                Stano
>
>
> diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
> index 8ba19bb..914a4fa 100644
> --- a/drivers/nvmem/mxs-ocotp.c
> +++ b/drivers/nvmem/mxs-ocotp.c
> @@ -94,7 +94,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
>         if (ret)
>                 goto close_banks;
>
> -       while (val_size) {
> +       while (val_size >= reg_size) {
>                 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
>                         /* fill up non-data register */
>                         *buf = 0;
> @@ -103,7 +103,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
>                 }
>
>                 buf++;
> -               val_size--;
> +               val_size -= reg_size;
>                 offset += reg_size;
>         }