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From: Greg KH on 25 May 2010 14:20
2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: Dan Carpenter <error27(a)gmail.com>

commit b0cc58a25d04160d39a80e436847eaa2fbc5aa09 upstream.

The original code doesn't take into consideration that the value of
MIXART_BA0_SIZE - pos can be less than zero which would lead to a large
unsigned value for "count".

Also I moved the check that read size is a multiple of 4 bytes below
the code that adjusts "count".

Signed-off-by: Dan Carpenter <error27(a)gmail.com>
Acked-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai(a)suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
sound/pci/mixart/mixart.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

--- a/sound/pci/mixart/mixart.c
+++ b/sound/pci/mixart/mixart.c
@@ -1160,13 +1160,15 @@ static long snd_mixart_BA0_read(struct s
unsigned long count, unsigned long pos)
{
struct mixart_mgr *mgr = entry->private_data;
+ unsigned long maxsize;

- count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
- if(count <= 0)
+ if (pos >= MIXART_BA0_SIZE)
return 0;
- if(pos + count > MIXART_BA0_SIZE)
- count = (long)(MIXART_BA0_SIZE - pos);
- if(copy_to_user_fromio(buf, MIXART_MEM( mgr, pos ), count))
+ maxsize = MIXART_BA0_SIZE - pos;
+ if (count > maxsize)
+ count = maxsize;
+ count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
+ if (copy_to_user_fromio(buf, MIXART_MEM(mgr, pos), count))
return -EFAULT;
return count;
}
@@ -1179,13 +1181,15 @@ static long snd_mixart_BA1_read(struct s
unsigned long count, unsigned long pos)
{
struct mixart_mgr *mgr = entry->private_data;
+ unsigned long maxsize;

- count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
- if(count <= 0)
+ if (pos > MIXART_BA1_SIZE)
return 0;
- if(pos + count > MIXART_BA1_SIZE)
- count = (long)(MIXART_BA1_SIZE - pos);
- if(copy_to_user_fromio(buf, MIXART_REG( mgr, pos ), count))
+ maxsize = MIXART_BA1_SIZE - pos;
+ if (count > maxsize)
+ count = maxsize;
+ count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
+ if (copy_to_user_fromio(buf, MIXART_REG(mgr, pos), count))
return -EFAULT;
return count;
}


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