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SubjectRe: [PATCH v1 07/10] Input: atmel_mxt_ts - zero terminate config firmware file
On Fri, Jul 20, 2018 at 10:51:19PM +0100, Nick Dyer wrote:
> From: Nick Dyer <nick.dyer@itdev.co.uk>
>
> We use sscanf to parse the configuration file, so it's necessary to zero
> terminate the configuration otherwise a truncated file can cause the
> parser to run off into uninitialised memory.
>
> Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 36 +++++++++++++++++-------
> 1 file changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 0ce126e918f1..2d1fddafb7f9 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -279,7 +279,7 @@ enum mxt_suspend_mode {
>
> /* Config update context */
> struct mxt_cfg {
> - const u8 *raw;
> + u8 *raw;
> size_t raw_size;
> off_t raw_pos;
>
> @@ -1451,14 +1451,21 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)
> u32 info_crc, config_crc, calculated_crc;
> u16 crc_start = 0;
>
> - cfg.raw = fw->data;
> + /* Make zero terminated copy of the OBP_RAW file */
> + cfg.raw = kzalloc(fw->size + 1, GFP_KERNEL);

kmemdup_nul()? I guess config it not that big to be concerned with
kmalloc() vs vmalloc() and allocation failures...

> + if (!cfg.raw)
> + return -ENOMEM;
> +
> + memcpy(cfg.raw, fw->data, fw->size);
> + cfg.raw[fw->size] = '\0';
> cfg.raw_size = fw->size;
>
> mxt_update_crc(data, MXT_COMMAND_REPORTALL, 1);
>
> if (strncmp(cfg.raw, MXT_CFG_MAGIC, strlen(MXT_CFG_MAGIC))) {
> dev_err(dev, "Unrecognised config file\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
>
> cfg.raw_pos = strlen(MXT_CFG_MAGIC);
> @@ -1470,7 +1477,8 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)
> &offset);
> if (ret != 1) {
> dev_err(dev, "Bad format\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
>
> cfg.raw_pos += offset;
> @@ -1478,26 +1486,30 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)
>
> if (cfg.info.family_id != data->info->family_id) {
> dev_err(dev, "Family ID mismatch!\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
>
> if (cfg.info.variant_id != data->info->variant_id) {
> dev_err(dev, "Variant ID mismatch!\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
>
> /* Read CRCs */
> ret = sscanf(cfg.raw + cfg.raw_pos, "%x%n", &info_crc, &offset);
> if (ret != 1) {
> dev_err(dev, "Bad format: failed to parse Info CRC\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
> cfg.raw_pos += offset;
>
> ret = sscanf(cfg.raw + cfg.raw_pos, "%x%n", &config_crc, &offset);
> if (ret != 1) {
> dev_err(dev, "Bad format: failed to parse Config CRC\n");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto release_raw;
> }
> cfg.raw_pos += offset;
>
> @@ -1530,8 +1542,10 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)
> MXT_INFO_CHECKSUM_SIZE;
> cfg.mem_size = data->mem_size - cfg.start_ofs;
> cfg.mem = kzalloc(cfg.mem_size, GFP_KERNEL);
> - if (!cfg.mem)
> - return -ENOMEM;
> + if (!cfg.mem) {
> + ret = -ENOMEM;
> + goto release_raw;
> + }
>
> ret = mxt_prepare_cfg_mem(data, &cfg);
> if (ret)
> @@ -1570,6 +1584,8 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *fw)
> /* T7 config may have changed */
> mxt_init_t7_power_cfg(data);
>
> +release_raw:
> + kfree(cfg.raw);
> release_mem:
> kfree(cfg.mem);
> return ret;
> --
> 2.17.1
>

--
Dmitry

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