On Mon, Feb 21, 2011 at 08:33:36PM -0800, mark gross wrote:
> On Fri, Feb 18, 2011 at 10:54:56AM +0900, Simon Horman wrote:
> > In "PM QoS: Correct pr_debug() misuse and improve parameter checks"
> > the parsing of the ASCII hex value was tightened. Unfortunately
> > it was tightened to the point where no value is valid.
> >
> > Root of the problem seems to lie in wheather the ASCII hex is followed
> > by a '\n' or not. My reading of the documentation is that the '\n' should
> > not be present. However the code previously only accepted that version.
> > The current code accepts neither. My fix is to accept both.
> >
> > Cc: Mark Gross <markgross@xxxxxxxxxxx>
> > Cc: Dan Carpenter <error27@xxxxxxxxx>
> > Cc: Rafael J. Wysocki <rjw@xxxxxxx>
> > Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
> >
> > ---
> > This appears to have been introduced around 2.6.36-rc4.
> > And was an @stable patch. As such I believe this change
> > is stable material.
> > ---
> > kernel/pm_qos_params.c | 7 ++++---
> > 1 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
> > index aeaa7f8..98a34ea 100644
> > --- a/kernel/pm_qos_params.c
> > +++ b/kernel/pm_qos_params.c
> > @@ -387,10 +387,11 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> > if (count == sizeof(s32)) {
> > if (copy_from_user(&value, buf, sizeof(s32)))
> > return -EFAULT;
> > - } else if (count == 11) { /* len('0x12345678/0') */
> > - if (copy_from_user(ascii_value, buf, 11))
> > + } else if (count == 11 || count == 10) { /* len('0x12345678\n') or
> shouldn't this be count ==12 ||count ==10?
> After taking Alan's advice and looking at strict_strtoul it looks like
> 10 and 12 are the numbers to use.
>
> Also playing with your dd test:
> mgross@mgt:~$ echo -n 0x12345678 | dd of=junk.bin
> 0+1 records in
> 0+1 records out
> 10 bytes (10 B) copied, 0.000368621 s, 27.1 kB/s
> mgross@mgt:~$ hexdump junk.bin
> 0000000 7830 3231 3433 3635 3837
> 000000a
> mgross@mgt:~$ echo 0x12345678 | dd of=junk.bin
> 0+1 records in
> 0+1 records out
> 11 bytes (11 B) copied, 0.000384755 s, 28.6 kB/s
> mgross@mgt:~$ hexdump junk.bin
> 0000000 7830 3231 3433 3635 3837 000a
> 000000b
>
> it looks like I have 10 or 12 bytes (but can't reconcile the dd output
> saying 11 bytes when hexdump is showing 12 )
on a 64 bit ubuntu box its 11 bytes that get sent to the kernel hexdump
must be padding the extra byte.>
> The following patch (untested) should make things work ok.
it doesn't work and I'm still debugging some straingess with strict_strtoul
it looks like its munging the string I'm passing in.
>
> diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
> index aeaa7f8..6cbce91 100644
> --- a/kernel/pm_qos_params.c
> +++ b/kernel/pm_qos_params.c
> @@ -381,19 +381,18 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> {
> s32 value;
> int x;
> - char ascii_value[11];
> + char ascii_value[12];
> struct pm_qos_request_list *pm_qos_req;
>
> if (count == sizeof(s32)) {
> if (copy_from_user(&value, buf, sizeof(s32)))
> return -EFAULT;
> - } else if (count == 11) { /* len('0x12345678/0') */
> - if (copy_from_user(ascii_value, buf, 11))
> + } else if (count == 10 || count == 12) { /* '0x12345678' or
} else if (count == 10 || count == 11) { /* '0x12345678' or
> + '0x12345678/n/0'*/
> + memset(ascii_value, 0, sizeof(ascii_value));
> + if (copy_from_user(ascii_value, buf, count))
if (copy_from_user(ascii_value, buf, 10))
> return -EFAULT;
> - if (strlen(ascii_value) != 10)
> - return -EINVAL;
> - x = sscanf(ascii_value, "%x", &value);
> - if (x != 1)
> + if (strict_strtoul(ascii_value,16,value) != 0)
^&value
its odd the array ascii_value is getting stomped on. Very strange.
I'm sure I'm doing something dumb. I'll keep working on this and send
an patch after it checks out.
--mark
> return -EINVAL;
> pr_debug("%s, %d, 0x%x\n", ascii_value, x, value);
> } else
>
> ------
> I'll test this tomorrow and do a proper posting (if it works right)
>
> --mark
> > + * len('0x12345678') */
> > + if (copy_from_user(ascii_value, buf, count))
> > return -EFAULT;
> > - if (strlen(ascii_value) != 10)
> > + if (strlen(ascii_value) != count)
> > return -EINVAL;
> > x = sscanf(ascii_value, "%x", &value);
> > if (x != 1)
> > --
> > 1.7.2.3
> >
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