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ath9k: dfs: Remove VLA usage

PATCH In review Kees Cook 2 participants 3 messages Apr 24, 2018 – Apr 25, 2018

Subsystems (3)
Networking Network drivers Qualcomm Atheros ATH9K wireless driver
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Kees Cook

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#0 lore raw

PATCH v3 1/1 ath9k: dfs: Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this redefines FFT_NUM_SAMPLES as a #define instead of const int, which still triggers gcc's VLA checking pass.

[1] https://lkml.org/lkml/2018/3/7/621

Co-developed-by Andreas Christoforou <[email protected]>
Signed-off-by Kees Cook <[email protected]>

---
v3: replace FFT_NUM_SAMPLES as a #define (Joe)

---
 drivers/net/wireless/ath/ath9k/dfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/net/wireless/ath/ath9k/dfs.c +2 -2
index 6fee9a464cce..e6e56a925121 100644
@@ -40,8 +40,8 @@ static const int BIN_DELTA_MIN		= 1;
 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);
+#define NUM_DIFFS	3
+#define FFT_NUM_SAMPLES	(NUM_DIFFS + 1)
 
 /* Threshold for difference of delta peaks */
 static const int MAX_DIFF		= 2;
Signature · 6 lines
2.7.4


-- 
Kees Cook
Pixel Security
#1 lore raw
Quoted 20 lines · Kees Cook

In the quest to remove all stack VLA usage from the kernel[1], this redefines FFT_NUM_SAMPLES as a #define instead of const int, which still triggers gcc's VLA checking pass.

[1] https://lkml.org/lkml/2018/3/7/621

Co-developed-by Andreas Christoforou <[email protected]>
Signed-off-by Kees Cook <[email protected]>

---
v3: replace FFT_NUM_SAMPLES as a #define (Joe)

---
 drivers/net/wireless/ath/ath9k/dfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/net/wireless/ath/ath9k/dfs.c +0 -0
index 6fee9a464cce..e6e56a925121 100644

drivers/net/wireless/ath/ath9k/dfs.c static const int BIN_DELTA_MIN = 1; · line 44

Quoted 7 lines
drivers/net/wireless/ath/ath9k/dfs.c +2 -2
@@ -40,8 +40,8 @@ static const int BIN_DELTA_MIN		= 1;
 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);
+#define NUM_DIFFS	3
+#define FFT_NUM_SAMPLES	(NUM_DIFFS + 1)

I have already applied an almost identical patch:

ath9k: dfs: remove accidental use of stack VLA

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=ath-next&id=9c27489a34548913baaaf3b2776e05d4a9389e3e

Signature · 1 line
Kalle Valo