Tavis Ormandy 462e635e5b install_special_mapping skips security_file_mmap check. ... The install_special_mapping routine (used, for example, to setup the vdso) skips the security check before insert_vm_struct, allowing a local attacker to bypass the mmap_min_addr security restriction by limiting the available pages for special mappings. bprm_mm_init() also skips the check, and although I don't think this can be used to bypass any restrictions, I don't see any reason not to have the security check. $ uname -m x86_64 $ cat /proc/sys/vm/mmap_min_addr 65536 $ cat install_special_mapping.s section .bss resb BSS_SIZE section .text global _start _start: mov eax, __NR_pause int 0x80 $ nasm -D__NR_pause=29 -DBSS_SIZE=0xfffed000 -f elf -o install_special_mapping.o install_special_mapping.s $ ld -m elf_i386 -Ttext=0x10000 -Tbss=0x11000 -o install_special_mapping install_special_mapping.o $ ./install_special_mapping & [1] 14303 $ cat /proc/14303/maps 0000f000-00010000 r-xp 00000000 00:00 0 [vdso] 00010000-00011000 r-xp 00001000 00:19 2453665 /home/taviso/install_special_mapping 00011000-ffffe000 rwxp 00000000 00:00 0 [stack] It's worth noting that Red Hat are shipping with mmap_min_addr set to 4096. Signed-off-by: Tavis Ormandy <taviso@google.com> Acked-by: Kees Cook <kees@ubuntu.com> Acked-by: Robert Swiecki <swiecki@google.com> [ Changed to not drop the error code - akpm ] Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2010-12-15 12:30:36 -08:00
..
backing-dev.c
bootmem.c
bounce.c
compaction.c
debug-pagealloc.c
dmapool.c
fadvise.c
failslab.c
filemap_xip.c
filemap.c
fremap.c
highmem.c
hugetlb.c
hwpoison-inject.c
init-mm.c
internal.h
Kconfig
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c
ksm.c
maccess.c
madvise.c
Makefile
memblock.c
memcontrol.c
memory_hotplug.c
memory-failure.c
memory.c
mempolicy.c
mempool.c
migrate.c
mincore.c
mlock.c
mm_init.c
mmap.c
mmu_context.c
mmu_notifier.c
mmzone.c
mprotect.c
mremap.c
msync.c
nommu.c
oom_kill.c
page_alloc.c
page_cgroup.c
page_io.c
page_isolation.c
page-writeback.c
pagewalk.c
percpu-km.c
percpu-vm.c
percpu.c
prio_tree.c
quicklist.c
readahead.c
rmap.c
shmem.c
slab.c
slob.c
slub.c
sparse-vmemmap.c
sparse.c
swap_state.c
swap.c
swapfile.c
thrash.c
truncate.c
util.c
vmalloc.c
vmscan.c
vmstat.c