[58/64] powerpc: Split memset() to avoid multi-field overflow

Message ID 20210727205855.411487-59-keescook@chromium.org
State Superseded
Headers show
Series
  • Introduce strict memcpy() bounds checking
Related show

Commit Message

Kees Cook July 27, 2021, 8:58 p.m.
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Instead of writing across a field boundary with memset(), move the call
to just the array, and an explicit zeroing of the prior field.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/macintosh/smu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Michael Ellerman Aug. 5, 2021, 11:36 a.m. | #1
Kees Cook <keescook@chromium.org> writes:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
>
> Instead of writing across a field boundary with memset(), move the call
> to just the array, and an explicit zeroing of the prior field.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/macintosh/smu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
> index 94fb63a7b357..59ce431da7ef 100644
> --- a/drivers/macintosh/smu.c
> +++ b/drivers/macintosh/smu.c
> @@ -848,7 +848,8 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
>  	cmd->read = cmd->info.devaddr & 0x01;
>  	switch(cmd->info.type) {
>  	case SMU_I2C_TRANSFER_SIMPLE:
> -		memset(&cmd->info.sublen, 0, 4);
> +		cmd->info.sublen = 0;
> +		memset(&cmd->info.subaddr, 0, 3);
>  		break;
>  	case SMU_I2C_TRANSFER_COMBINED:
>  		cmd->info.devaddr &= 0xfe;
> -- 
> 2.30.2

Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>

cheers

Patch

diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
index 94fb63a7b357..59ce431da7ef 100644
--- a/drivers/macintosh/smu.c
+++ b/drivers/macintosh/smu.c
@@ -848,7 +848,8 @@  int smu_queue_i2c(struct smu_i2c_cmd *cmd)
 	cmd->read = cmd->info.devaddr & 0x01;
 	switch(cmd->info.type) {
 	case SMU_I2C_TRANSFER_SIMPLE:
-		memset(&cmd->info.sublen, 0, 4);
+		cmd->info.sublen = 0;
+		memset(&cmd->info.subaddr, 0, 3);
 		break;
 	case SMU_I2C_TRANSFER_COMBINED:
 		cmd->info.devaddr &= 0xfe;