- NetBSD Manual Pages
MPROTECT(2) NetBSD System Calls Manual MPROTECT(2)
Powered by man-cgi (2021-06-01).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
mprotect -- control the protection of pages
Standard C Library (libc, -lc)
mprotect(void *addr, size_t len, int prot);
The mprotect system call changes the specified pages to have protection
prot. Not all implementations will guarantee protection on a page basis;
the granularity of protection changes may be as large as an entire
The protections (region accessibility) are specified in the prot argument
by OR'ing the following values:
PROT_EXEC Pages may be executed.
PROT_READ Pages may be read.
PROT_WRITE Pages may be written.
PROT_NONE Placeholder when requesting no access permission.
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
[EACCES] A memory protection violation occurred.
The PROT_EXEC flag was attempted on pages which belong
to a file system mounted with the NOEXEC flag.
The new protection is less restrictive than the pro-
tection originally set with mmap(2).
PaX mprotect restrictions prohibit the requested pro-
[EINVAL] An invalid memory range, or invalid parameters were
[ENOMEM] A resource shortage occurred while internally calling
madvise(2), mincore(2), msync(2), munmap(2)
The mprotect function first appeared in SunOS 4.0 and subsequently
NetBSD 9.99 September 8, 2019 NetBSD 9.99