niloufer@utdallas.edu (Niloufer Vajifdar) writes:
> hi,
>
> i'm new to linux kernel programming and i'm having the following problem:
>
> When trying to use the sys_read and sys_write calls from within another
> system call the return value is -14 (bad address EFAULT). This seems to be
> happening because the 'access_ok' function is not allowing the access to
> the buffer being used to read or write.
>
> Could someone explain why this is happening? Is it wrong to use
> sys_read/sys_write through another system call?
You have to do
mm_segment_t oldfs = get_fs(); set_fs(KERNEL_DS);
/* call system call with kernel pointers */
set_fs(oldfs):
Otherwise it would be possible for every user to access kernel memory
by passing pointers to it to system calls.
-Andi
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This archive was generated by hypermail 2b29 : Sun Jan 23 2000 - 21:00:28 EST