x86: fix norandmaps/ADDR_NO_RANDOMIZE
Subsystems (5)
v2 cover x86: fix norandmaps/ADDR_NO_RANDOMIZE
v2:
- mention ADDR_NO_RANDOMIZE in subect/changelog
- add the acks
Oleg.
arch/x86/mm/mmap.c | 7 +++---- fs/binfmt_elf.c | 3 +-- 2 files changed, 4 insertions(+), 6 deletions(-)
PATCH v2 1/2 x86: fix norandmaps/ADDR_NO_RANDOMIZE
Documentation/admin-guide/kernel-parameters.txt says:
norandmaps Don't use address space randomization. Equivalent
to echo 0 > /proc/sys/kernel/randomize_va_space
but it doesn't work because arch_rnd() which is used to randomize mm->mmap_base returns a random value unconditionally. And as Kirill pointed out, ADDR_NO_RANDOMIZE is broken by the same reason.
Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
--- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
arch/x86/mm/mmap.c +2 -2
@@ -79,13 +79,13 @@ static int mmap_is_legacy(void)static unsigned long arch_rnd (unsigned int rndbits) { +if (!(current->flags &PF_RANDOMIZE )) +return 0 ;return (get_random_long () & ((1UL << rndbits) -1 )) <<PAGE_SHIFT ; }unsigned long arch_mmap_rnd (void ) { -if (!(current->flags &PF_RANDOMIZE )) -return 0 ;return arch_rnd (mmap_is_ia32 () ? mmap32_rnd_bits : mmap64_rnd_bits); }
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:x86/urgent] x86: Fix norandmaps/ADDR_NO_RANDOMIZE
x86: Fix norandmaps/ADDR_NO_RANDOMIZE
Commit-ID: 47ac5484fd961420e5ec0bb5b972fde381f57365 Gitweb: http://git.kernel.org/tip/47ac5484fd961420e5ec0bb5b972fde381f57365 Author: Oleg Nesterov <[email protected]> AuthorDate: Tue, 15 Aug 2017 17:39:52 +0200 Committer: Thomas Gleixner <[email protected]> CommitDate: Wed, 16 Aug 2017 20:32:01 +0200
x86: Fix norandmaps/ADDR_NO_RANDOMIZE
Documentation/admin-guide/kernel-parameters.txt says:
norandmaps Don't use address space randomization. Equivalent
to echo 0 > /proc/sys/kernel/randomize_va_space
but it doesn't work because arch_rnd() which is used to randomize mm->mmap_base returns a random value unconditionally. And as Kirill pointed out, ADDR_NO_RANDOMIZE is broken by the same reason.
Just shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
--- arch/x86/mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
arch/x86/mm/mmap.c +2 -2
@@ -79,13 +79,13 @@ static int mmap_is_legacy(void)static unsigned long arch_rnd (unsigned int rndbits) { +if (!(current->flags &PF_RANDOMIZE )) +return 0 ;return (get_random_long () & ((1UL << rndbits) -1 )) <<PAGE_SHIFT ; }unsigned long arch_mmap_rnd (void ) { -if (!(current->flags &PF_RANDOMIZE )) -return 0 ;return arch_rnd (mmap_is_ia32 () ? mmap32_rnd_bits : mmap64_rnd_bits); }
PATCH v2 2/2 x86/elf: remove the unnecessary ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top()
In reply to Oleg NesterovPF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not set, no need to re-check after that.
--- arch/x86/mm/mmap.c | 3 +-- fs/binfmt_elf.c | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-)
arch/x86/mm/mmap.c +1 -2
@@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)static unsigned long stack_maxrandom_size (unsigned long task_size) {unsigned long max =0 ; -if ((current->flags &PF_RANDOMIZE ) && - !(current->personality &ADDR_NO_RANDOMIZE )) { +if (current->flags &PF_RANDOMIZE ) { max = (-1UL ) &__STACK_RND_MASK (task_size ==tasksize_32bit ()); max <<=PAGE_SHIFT ; }
fs/binfmt_elf.c +1 -2
@@ -664,8 +664,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top) {unsigned long random_variable =0 ; -if ((current->flags &PF_RANDOMIZE ) && - !(current->personality &ADDR_NO_RANDOMIZE )) { +if (current->flags &PF_RANDOMIZE ) { random_variable =get_random_long (); random_variable &=STACK_RND_MASK ; random_variable <<=PAGE_SHIFT ;
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:x86/urgent] x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks
x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks
Commit-ID: 01578e36163cdd0e4fd61d9976de15f13364e26d Gitweb: http://git.kernel.org/tip/01578e36163cdd0e4fd61d9976de15f13364e26d Author: Oleg Nesterov <[email protected]> AuthorDate: Tue, 15 Aug 2017 17:40:11 +0200 Committer: Thomas Gleixner <[email protected]> CommitDate: Wed, 16 Aug 2017 20:32:02 +0200
x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks
The ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top() are not required.
PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not set, no need to re-check after that.
--- arch/x86/mm/mmap.c | 3 +-- fs/binfmt_elf.c | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-)
arch/x86/mm/mmap.c +1 -2
@@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)static unsigned long stack_maxrandom_size (unsigned long task_size) {unsigned long max =0 ; -if ((current->flags &PF_RANDOMIZE ) && - !(current->personality &ADDR_NO_RANDOMIZE )) { +if (current->flags &PF_RANDOMIZE ) { max = (-1UL ) &__STACK_RND_MASK (task_size ==tasksize_32bit ()); max <<=PAGE_SHIFT ; }
fs/binfmt_elf.c +1 -2
@@ -664,8 +664,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top) {unsigned long random_variable =0 ; -if ((current->flags &PF_RANDOMIZE ) && - !(current->personality &ADDR_NO_RANDOMIZE )) { +if (current->flags &PF_RANDOMIZE ) { random_variable =get_random_long (); random_variable &=STACK_RND_MASK ; random_variable <<=PAGE_SHIFT ;