Author: kib
Date: Sat Jun 24 17:04:27 2017
New Revision: 320318
URL: https://svnweb.freebsd.org/changeset/base/320318
Log:
Use address space guard to implement inter-segment gap.
Rtld checks and use old MAP_ANON/PROT_NONE method of creating gap if
running on old kernel.
Reviewed by: alc, markj
Tested by: pho, Qualys
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/libexec/rtld-elf/map_object.c
Modified: head/libexec/rtld-elf/map_object.c
==============================================================================
--- head/libexec/rtld-elf/map_object.c Sat Jun 24 17:01:11 2017
(r320317)
+++ head/libexec/rtld-elf/map_object.c Sat Jun 24 17:04:27 2017
(r320318)
@@ -41,6 +41,8 @@
static Elf_Ehdr *get_elf_header(int, const char *, const struct stat *);
static int convert_flags(int); /* Elf flags -> mmap flags */
+int __getosreldate(void);
+
/*
* Map a shared object into memory. The "fd" argument is a file descriptor,
* which must be open on the object and positioned at its beginning.
@@ -190,7 +192,8 @@ map_object(int fd, const char *path, const struct stat
base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
mapsize = base_vlimit - base_vaddr;
base_addr = (caddr_t) base_vaddr;
- base_flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE;
+ base_flags = __getosreldate() >= P_OSREL_MAP_GUARD ? MAP_GUARD :
+ MAP_PRIVATE | MAP_ANON | MAP_NOCORE;
if (npagesizes > 1 && round_page(segs[0]->p_filesz) >= pagesizes[1])
base_flags |= MAP_ALIGNED_SUPER;
if (base_vaddr != 0)
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