Mailing List Archive

direct dereferencing from user-supplied address

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/media/dvb/ttpci/av7110_av.c | 34 +++++++++++++++++++++++++++-------
1 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/media/dvb/ttpci/av7110_av.c b/drivers/media/dvb/ttpci/av7110_av.c
index 3e6b650..ec55a96 100644
--- a/drivers/media/dvb/ttpci/av7110_av.c
+++ b/drivers/media/dvb/ttpci/av7110_av.c
@@ -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
--
1.5.3.GIT


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