Ok guys, I have one more question on this assignment :-) I successfully read in the data using copy_from_user and then I did some mangling of the data which I verified worked properly. Now I want to put it back into user space, so I use: If (copy_to_user(buf, tbuf2, count)) Buf is defined in the parameter list of my function as: Const char __user * buf Tbuf2 is defined as Char *tbuf; And count is just an int. I get a compile time error: /home/seed/hw5/hookme.c:128: warning: passing argument 1 of ???copy_to_user??? discards qualifiers from pointer target type Any good ideas on why this occurring and how I can fix it? Thanks in advance for any help! -----Original Message----- From: Jason White [mailto:jason@xxxxxxxxxxxx] Sent: Thursday, July 18, 2013 4:43 PM To: speakup at linux-speakup.org Subject: Re: OT: kernel oops Chris Brannon <chris at the-brannons.com> wrote: > Don Raikes <don.raikes at oracle.com> writes: > > > The section of code that is having problems looks like this: > *SNIP* > > if (copy_from_user(&tbuf, buf, count)) > > This line is your problem. You are passing a > pointer-to-pointer-to-character (char **) as the first argument to > copy_from_user, but you should be passing char * instead. So ditch > the ampersand, and all will be right with the world! > I could give you a thorough explanation of why this is failing, if you > like, but to make a long story short, this line of code is smashing > the stack! In other words, you're passing it the address of the pointer to the buffer, rather than the pointer itself, which holds the address of the buffer. _______________________________________________ Speakup mailing list Speakup at linux-speakup.org http://linux-speakup.org/cgi-bin/mailman/listinfo/speakup
