On 03/10/2018 05:12 PM, Kees Cook wrote:
On Sat, Mar 10, 2018 at 3:06 PM, Arend van Spriel
<arend.vanspriel@xxxxxxxxxxxx> wrote:
On 3/9/2018 1:30 PM, Andreas Christoforou wrote:
The kernel would like to have all stack VLA usage removed.
I think there was a remark made earlier to give more explanation here. It
should explain why we want "VLA on stack" removed.
Signed-off-by: Andreas Christoforou <andreaschristofo@xxxxxxxxx>
---
drivers/net/wireless/ath/ath9k/dfs.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/dfs.c
b/drivers/net/wireless/ath/ath9k/dfs.c
index 6fee9a4..cfb0f84 100644
--- a/drivers/net/wireless/ath/ath9k/dfs.c
+++ b/drivers/net/wireless/ath/ath9k/dfs.c
@@ -41,7 +41,6 @@ static const int BIN_DELTA_MAX = 10;
/* we need at least 3 deltas / 4 samples for a reliable chirp detection
*/
#define NUM_DIFFS 3
-static const int FFT_NUM_SAMPLES = (NUM_DIFFS + 1);
What about this instead?
#define FFT_NUM_SAMPLES (NUM_DIFFS + 1)
/* Threshold for difference of delta peaks */
static const int MAX_DIFF = 2;
@@ -101,7 +100,7 @@ static bool ath9k_check_chirping(struct ath_softc *sc,
u8 *data,
int datalen, bool is_ctl, bool is_ext)
{
int i;
- int max_bin[FFT_NUM_SAMPLES];
+ int max_bin[NUM_DIFFS + 1];
Just wondering. Is this actually a VLA. FFT_NUM_SAMPLES was static const so
not really going to show a lot of variation. This array will always have the
same size on the stack.
The problem is that it's not a "constant expression", so the compiler
frontend still yells about it under -Wvla. I would characterize this
mainly as a fix for "accidental VLA" or "misdetected VLA" or something
like that. AIUI, there really isn't a functional change here.
-Kees
--
Gustavo
