Messages in this thread | | | Date | Wed, 22 Feb 2006 00:07:25 +0100 | From | "Jesper Juhl" <> | Subject | Re: [PATCH] ISDN: fix copy_to_user() unused result warning in isdn_ppp |
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On 2/22/06, Karsten Keil <kkeil@suse.de> wrote: > On Tue, Feb 21, 2006 at 11:14:15PM +0100, Jesper Juhl wrote: > > From: Jesper Juhl <jesper.juhl@gmail.com> > > > > > > Fix compile warning about copy_to_user() unused result in isdn_ppp.c > > drivers/isdn/i4l/isdn_ppp.c:785: warning: ignoring return value of `copy_to_user', declared with attribute warn_unused_result > > > > > > Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> > > > > --- > > > > drivers/isdn/i4l/isdn_ppp.c | 5 ++++- > > 1 files changed, 4 insertions(+), 1 deletion(-) > > > > --- linux-2.6.16-rc4-mm1-orig/drivers/isdn/i4l/isdn_ppp.c 2006-01-03 04:21:10.000000000 +0100 > > +++ linux-2.6.16-rc4-mm1/drivers/isdn/i4l/isdn_ppp.c 2006-02-21 23:07:57.000000000 +0100 > > @@ -782,7 +782,10 @@ isdn_ppp_read(int min, struct file *file > > is->first = b; > > > > spin_unlock_irqrestore(&is->buflock, flags); > > - copy_to_user(buf, save_buf, count); > > + if (copy_to_user(buf, save_buf, count)) { > > + kfree(save_buf); > > + return -EFAULT; > > + } > > kfree(save_buf); > > > > return count; > > What about: > > --- linux-2.6.16-rc4-mm1-orig/drivers/isdn/i4l/isdn_ppp.c 2006-01-03 04:21:10.000000000 +0100 > +++ linux-2.6.16-rc4-mm1/drivers/isdn/i4l/isdn_ppp.c 2006-02-21 23:07:57.000000000 +0100 > @@ -782,7 +782,8 @@ isdn_ppp_read(int min, struct file *file > is->first = b; > > spin_unlock_irqrestore(&is->buflock, flags); > - copy_to_user(buf, save_buf, count); > + if (copy_to_user(buf, save_buf, count)) > + count = -EFAULT; > kfree(save_buf); > > return count; > > should result in a conditional move instead of jumps. >
I actually considered that, but decided against it since I thought it would be confusing use / misuse of 'count'.
Either version is fine by me. It's not likely to get hit in any case due to the verify_area() call further up in the code.
> But I'm OK with the original patch as well, for both version you can add > > Signed-off-by: Karsten Keil <kkeil@suse.de> >
Thanks.
Andrew: could you please apply either my or Karsten's version to -mm ?
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