[PATCH AUTOSEL for-3.18 17/27] ALSA: vx: Fix possible transfer overflow

["Levin, Alexander (Sasha Levin)" <alexander.levin@one.verizon.com>]

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit 874e1f6fad9a5184b67f4cee37c1335cd2cc5677 ]

The pseudo DMA transfer codes in VX222 and VX-pocket driver have a
slight bug where they check the buffer boundary wrongly, and may
overflow.  Also, the zero sample count might be handled badly for the
playback (although it shouldn't happen in theory).  This patch
addresses these issues.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=141541
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 sound/drivers/vx/vx_pcm.c   |  6 ++++--
 sound/pci/vx222/vx222_ops.c | 12 ++++++------
 sound/pcmcia/vx/vxp_ops.c   | 12 ++++++------
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/sound/drivers/vx/vx_pcm.c b/sound/drivers/vx/vx_pcm.c
index 69f252585780..ea7b377f0378 100644
--- a/sound/drivers/vx/vx_pcm.c
+++ b/sound/drivers/vx/vx_pcm.c
@@ -1048,8 +1048,10 @@ static void vx_pcm_capture_update(struct vx_core *chip, struct snd_pcm_substream
 		/* ok, let's accelerate! */
 		int align = pipe->align * 3;
 		space = (count / align) * align;
-		vx_pseudo_dma_read(chip, runtime, pipe, space);
-		count -= space;
+		if (space > 0) {
+			vx_pseudo_dma_read(chip, runtime, pipe, space);
+			count -= space;
+		}
 	}
 	/* read the rest of bytes */
 	while (count > 0) {
diff --git a/sound/pci/vx222/vx222_ops.c b/sound/pci/vx222/vx222_ops.c
index 2d1570273e99..5c541ed723dd 100644
--- a/sound/pci/vx222/vx222_ops.c
+++ b/sound/pci/vx222/vx222_ops.c
@@ -264,12 +264,12 @@ static void vx2_dma_write(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 
 	/* Transfer using pseudo-dma.
 	 */
-	if (offset + count > pipe->buffer_bytes) {
+	if (offset + count >= pipe->buffer_bytes) {
 		int length = pipe->buffer_bytes - offset;
 		count -= length;
 		length >>= 2; /* in 32bit words */
 		/* Transfer using pseudo-dma. */
-		while (length-- > 0) {
+		for (; length > 0; length--) {
 			outl(cpu_to_le32(*addr), port);
 			addr++;
 		}
@@ -279,7 +279,7 @@ static void vx2_dma_write(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	pipe->hw_ptr += count;
 	count >>= 2; /* in 32bit words */
 	/* Transfer using pseudo-dma. */
-	while (count-- > 0) {
+	for (; count > 0; count--) {
 		outl(cpu_to_le32(*addr), port);
 		addr++;
 	}
@@ -302,12 +302,12 @@ static void vx2_dma_read(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	vx2_setup_pseudo_dma(chip, 0);
 	/* Transfer using pseudo-dma.
 	 */
-	if (offset + count > pipe->buffer_bytes) {
+	if (offset + count >= pipe->buffer_bytes) {
 		int length = pipe->buffer_bytes - offset;
 		count -= length;
 		length >>= 2; /* in 32bit words */
 		/* Transfer using pseudo-dma. */
-		while (length-- > 0)
+		for (; length > 0; length--)
 			*addr++ = le32_to_cpu(inl(port));
 		addr = (u32 *)runtime->dma_area;
 		pipe->hw_ptr = 0;
@@ -315,7 +315,7 @@ static void vx2_dma_read(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	pipe->hw_ptr += count;
 	count >>= 2; /* in 32bit words */
 	/* Transfer using pseudo-dma. */
-	while (count-- > 0)
+	for (; count > 0; count--)
 		*addr++ = le32_to_cpu(inl(port));
 
 	vx2_release_pseudo_dma(chip);
diff --git a/sound/pcmcia/vx/vxp_ops.c b/sound/pcmcia/vx/vxp_ops.c
index 281972913c32..56aa1ba73ccc 100644
--- a/sound/pcmcia/vx/vxp_ops.c
+++ b/sound/pcmcia/vx/vxp_ops.c
@@ -369,12 +369,12 @@ static void vxp_dma_write(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	unsigned short *addr = (unsigned short *)(runtime->dma_area + offset);
 
 	vx_setup_pseudo_dma(chip, 1);
-	if (offset + count > pipe->buffer_bytes) {
+	if (offset + count >= pipe->buffer_bytes) {
 		int length = pipe->buffer_bytes - offset;
 		count -= length;
 		length >>= 1; /* in 16bit words */
 		/* Transfer using pseudo-dma. */
-		while (length-- > 0) {
+		for (; length > 0; length--) {
 			outw(cpu_to_le16(*addr), port);
 			addr++;
 		}
@@ -384,7 +384,7 @@ static void vxp_dma_write(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	pipe->hw_ptr += count;
 	count >>= 1; /* in 16bit words */
 	/* Transfer using pseudo-dma. */
-	while (count-- > 0) {
+	for (; count > 0; count--) {
 		outw(cpu_to_le16(*addr), port);
 		addr++;
 	}
@@ -411,12 +411,12 @@ static void vxp_dma_read(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	if (snd_BUG_ON(count % 2))
 		return;
 	vx_setup_pseudo_dma(chip, 0);
-	if (offset + count > pipe->buffer_bytes) {
+	if (offset + count >= pipe->buffer_bytes) {
 		int length = pipe->buffer_bytes - offset;
 		count -= length;
 		length >>= 1; /* in 16bit words */
 		/* Transfer using pseudo-dma. */
-		while (length-- > 0)
+		for (; length > 0; length--)
 			*addr++ = le16_to_cpu(inw(port));
 		addr = (unsigned short *)runtime->dma_area;
 		pipe->hw_ptr = 0;
@@ -424,7 +424,7 @@ static void vxp_dma_read(struct vx_core *chip, struct snd_pcm_runtime *runtime,
 	pipe->hw_ptr += count;
 	count >>= 1; /* in 16bit words */
 	/* Transfer using pseudo-dma. */
-	while (count-- > 1)
+	for (; count > 1; count--)
 		*addr++ = le16_to_cpu(inw(port));
 	/* Disable DMA */
 	pchip->regDIALOG &= ~VXP_DLG_DMAREAD_SEL_MASK;
-- 
2.11.0