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.TH "ACCESS_OK" 9 "August 2005" "Kernel Hackers Manual" "LINUX"
.SH NAME
access_ok \- Checks if a user space pointer is valid
.SH "SYNOPSIS"
.ad l
.hy 0
.HP 12
\fBaccess_ok\ \fR\ (\fItype\fR, \fIaddr\fR, \fIsize\fR);
.ad
.hy

.SH "ARGUMENTS"

.TP
\fItype\fR
Type of access: \fBVERIFY_READ\fR or \fBVERIFY_WRITE\fR\&. Note that \fBVERIFY_WRITE\fR is a superset of \fBVERIFY_READ\fR \- if it is safe to write to a block, it is always safe to read from it\&.

.TP
\fIaddr\fR
User space pointer to start of block to check

.TP
\fIsize\fR
Size of block to check

.SH "CONTEXT"

.PP
User context only\&. This function may sleep\&.

.SH "DESCRIPTION"

.PP
Checks if a pointer to a block of memory in user space is valid\&.

.PP
Returns true (nonzero) if the memory block may be valid, false (zero) if it is definitely invalid\&.

.PP
Note that, depending on architecture, this function probably just checks that the pointer is in the user space range \- after calling this function, memory access functions may still return \-EFAULT\&.