[PATCH alsa-utils 0/5] aplay: Fix bugs in peak calculations

[PATCH alsa-utils 0/5] aplay: Fix bugs in peak calculations

[Takashi Iwai]

The code in aplay for sample peak calculations and VU-meter
representation seems to have a lot of bugs.  Let's fix them.


Takashi

===

Takashi Iwai (5):
  aplay: Fix conversion of unsigned samples in peak calculation
  aplay: Handle 16bit sample negative overflow in peak calculations
  aplay: Don't pass most negative integer to abs() in peak calculations
  aplay: Handle upper bound in peak calculations
  aplay: Fix out-of-bound access in stereo VU meter drawing

 aplay/aplay.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

-- 
2.26.2

[PATCH alsa-utils 1/5] aplay: Fix conversion of unsigned samples in peak calculation

[Takashi Iwai]

The XOR with the mask has to be applied before calculating abs value.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 aplay/aplay.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index cc51dcb48bba..91af244edb60 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1828,7 +1828,8 @@ static void compute_max_peak(u_char *data, size_t samples)
 				sval = le16toh(*valp);
 			else
 				sval = be16toh(*valp);
-			sval = abs(sval) ^ mask;
+			sval ^= mask;
+			sval = abs(sval);
 			if (max_peak[c] < sval)
 				max_peak[c] = sval;
 			valp++;
@@ -1848,11 +1849,12 @@ static void compute_max_peak(u_char *data, size_t samples)
 			} else {
 				val = (valp[0]<<16) | (valp[1]<<8) | valp[2];
 			}
+			val ^= mask;
 			/* Correct signed bit in 32-bit value */
 			if (val & (1<<(bits_per_sample-1))) {
 				val |= 0xff<<24;	/* Negate upper bits too */
 			}
-			val = abs(val) ^ mask;
+			val = abs(val);
 			if (max_peak[c] < val)
 				max_peak[c] = val;
 			valp += 3;
@@ -1871,7 +1873,8 @@ static void compute_max_peak(u_char *data, size_t samples)
 				val = le32toh(*valp);
 			else
 				val = be32toh(*valp);
-			val = abs(val) ^ mask;
+			val ^= mask;
+			val = abs(val);
 			if (max_peak[c] < val)
 				max_peak[c] = val;
 			valp++;
-- 
2.26.2

[PATCH alsa-utils 2/5] aplay: Handle 16bit sample negative overflow in peak calculations

[Takashi Iwai]

The handling of 16bit samples in the peak calculations has a bug when
a sample with 0x8000 is passed.  As abs() treats 32bit int, it returns
0x8000.  And yet the code stores back into 16bit value again.

To fix that overflow, use 32bit value (i.e. val instead of sval) for
the further calculations.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 aplay/aplay.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index 91af244edb60..c884346c9f25 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1829,9 +1829,9 @@ static void compute_max_peak(u_char *data, size_t samples)
 			else
 				sval = be16toh(*valp);
 			sval ^= mask;
-			sval = abs(sval);
-			if (max_peak[c] < sval)
-				max_peak[c] = sval;
+			val = abs(sval);
+			if (max_peak[c] < val)
+				max_peak[c] = val;
 			valp++;
 			if (vumeter == VUMETER_STEREO)
 				c = !c;
-- 
2.26.2

[PATCH alsa-utils 3/5] aplay: Don't pass most negative integer to abs() in peak calculations

[Takashi Iwai]

The return value from abs() for the most negative integer is
undefined.  Cap it properly for the 32bit sample handling.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 aplay/aplay.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index c884346c9f25..2543de5b6cd8 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1874,7 +1874,10 @@ static void compute_max_peak(u_char *data, size_t samples)
 			else
 				val = be32toh(*valp);
 			val ^= mask;
-			val = abs(val);
+			if (val == 0x80000000U)
+				val = 0x7fffffff;
+			else
+				val = abs(val);
 			if (max_peak[c] < val)
 				max_peak[c] = val;
 			valp++;
-- 
2.26.2

[PATCH alsa-utils 4/5] aplay: Handle upper bound in peak calculations

[Takashi Iwai]

Make sure that the calculated max_peak[] won't go beyond the sample
max resolution.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 aplay/aplay.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index 2543de5b6cd8..a51a37ba34bd 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1898,6 +1898,8 @@ static void compute_max_peak(u_char *data, size_t samples)
 		max = 0x7fffffff;
 
 	for (c = 0; c < ichans; c++) {
+		if (max_peak[c] > max)
+			max_peak[c] = max;
 		if (bits_per_sample > 16)
 			perc[c] = max_peak[c] / (max / 100);
 		else
-- 
2.26.2

[PATCH alsa-utils 5/5] aplay: Fix out-of-bound access in stereo VU meter drawing

[Takashi Iwai]

The left channel drawing of a stereo VU meter has a bug where it may
access a negative array index.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 aplay/aplay.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/aplay/aplay.c b/aplay/aplay.c
index a51a37ba34bd..63a4e3437fd9 100644
--- a/aplay/aplay.c
+++ b/aplay/aplay.c
@@ -1758,10 +1758,12 @@ static void print_vu_meter_stereo(int *perc, int *maxperc)
 		if (c)
 			memset(line + bar_length + 6 + 1, '#', p);
 		else
-			memset(line + bar_length - p - 1, '#', p);
-		p = maxperc[c] * bar_length / 100;
-		if (p > bar_length)
-			p = bar_length;
+			memset(line + bar_length - p, '#', p);
+		p = maxperc[c] * bar_length / 100 - 1;
+		if (p < 0)
+			p = 0;
+		else if (p >= bar_length)
+			p = bar_length - 1;
 		if (c)
 			line[bar_length + 6 + 1 + p] = '+';
 		else
-- 
2.26.2