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V4L/DVB (7957): fix the roothole in av7110_av.c

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direct dereferencing from user-supplied address

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Al Viro 2008-05-21 00:30:41 -03:00 committed by Mauro Carvalho Chehab
parent f34ec12a17
commit a230e55d92
1 changed files with 27 additions and 7 deletions
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34
drivers/media/dvb/ttpci/av7110_av.c
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@ -965,8 +965,9 @@ static u8 iframe_header[] = { 0x00, 0x00, 0x01, 0xe0, 0x00, 0x00, 0x80, 0x00, 0x
static int play_iframe(struct av7110 *av7110, char __user *buf, unsigned int len, int nonblock)
{
int i, n;
unsigned i, n;
int progressive = 0;
int match = 0;
dprintk(2, "av7110:%p, \n", av7110);
@ -975,12 +976,31 @@ static int play_iframe(struct av7110 *av7110, char __user *buf, unsigned int len
return -EBUSY;
}
for (i = 0; i < len - 5; i++) {
/* get progressive flag from picture extension */
if (buf[i] == 0x00 && buf[i+1] == 0x00 &&
buf[i+2] == 0x01 && (unsigned char)buf[i+3] == 0xb5 &&
(buf[i+4] & 0xf0) == 0x10)
progressive = buf[i+5] & 0x08;
/* search in buf for instances of 00 00 01 b5 1? */
for (i = 0; i < len; i++) {
unsigned char c;
if (get_user(c, buf + i))
return -EFAULT;
if (match == 5) {
progressive = c & 0x08;
match = 0;
}
if (c == 0x00) {
match = (match == 1 || match == 2) ? 2 : 1;
continue;
}
switch (match++) {
case 2: if (c == 0x01)
continue;
break;
case 3: if (c == 0xb5)
continue;
break;
case 4: if ((c & 0xf0) == 0x10)
continue;
break;
}
match = 0;
}
/* setting n always > 1, fixes problems when playing stillframes