Message ID | 20170907135138.2199-2-kleber.souza@canonical.com |
---|---|
State | New |
Headers | show |
Series | Fix for LP: #1715636 | expand |
On 07/09/17 14:51, Kleber Sacilotto de Souza wrote: > From: Kees Cook <keescook@chromium.org> > > BugLink: http://bugs.launchpad.net/bugs/1715636 > > Moving the x86_64 and arm64 PIE base from 0x555555554000 to 0x000100000000 > broke AddressSanitizer. This is a partial revert of: > > eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") > 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") > > The AddressSanitizer tool has hard-coded expectations about where > executable mappings are loaded. > > The motivation for changing the PIE base in the above commits was to > avoid the Stack-Clash CVEs that allowed executable mappings to get too > close to heap and stack. This was mainly a problem on 32-bit, but the > 64-bit bases were moved too, in an effort to proactively protect those > systems (proofs of concept do exist that show 64-bit collisions, but > other recent changes to fix stack accounting and setuid behaviors will > minimize the impact). > > The new 32-bit PIE base is fine for ASan (since it matches the ET_EXEC > base), so only the 64-bit PIE base needs to be reverted to let x86 and > arm64 ASan binaries run again. Future changes to the 64-bit PIE base on > these architectures can be made optional once a more dynamic method for > dealing with AddressSanitizer is found. (e.g. always loading PIE into > the mmap region for marked binaries.) > > Link: http://lkml.kernel.org/r/20170807201542.GA21271@beast > Fixes: eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") > Fixes: 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") > Signed-off-by: Kees Cook <keescook@chromium.org> > Reported-by: Kostya Serebryany <kcc@google.com> > Acked-by: Will Deacon <will.deacon@arm.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: <stable@vger.kernel.org> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > (cherry picked from commit c715b72c1ba406f133217b509044c38d8e714a37) > Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> > --- > arch/arm64/include/asm/elf.h | 4 ++-- > arch/x86/include/asm/elf.h | 4 ++-- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h > index 9e11dbe1cec3..329c127e13dc 100644 > --- a/arch/arm64/include/asm/elf.h > +++ b/arch/arm64/include/asm/elf.h > @@ -121,10 +121,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; > > /* > * This is the base location for PIE (ET_DYN with INTERP) loads. On > - * 64-bit, this is raised to 4GB to leave the entire 32-bit address > + * 64-bit, this is above 4GB to leave the entire 32-bit address > * space open for things that want to use the area for 32-bit pointers. > */ > -#define ELF_ET_DYN_BASE 0x100000000UL > +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) > > /* > * When the program starts, a1 contains a pointer to a function to be > diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h > index 07cf288b692e..bcd3d6199464 100644 > --- a/arch/x86/include/asm/elf.h > +++ b/arch/x86/include/asm/elf.h > @@ -247,11 +247,11 @@ extern int force_personality32; > > /* > * This is the base location for PIE (ET_DYN with INTERP) loads. On > - * 64-bit, this is raised to 4GB to leave the entire 32-bit address > + * 64-bit, this is above 4GB to leave the entire 32-bit address > * space open for things that want to use the area for 32-bit pointers. > */ > #define ELF_ET_DYN_BASE (mmap_is_ia32() ? 0x000400000UL : \ > - 0x100000000UL) > + (TASK_SIZE / 3 * 2)) > > /* This yields a mask that user programs can use to figure out what > instruction set this CPU supports. This could be done in user space, > Clean cherry pick. Seems to do the right thing. Acked-by: Colin Ian King <colin.king@canonical.com>
On 07.09.2017 15:51, Kleber Sacilotto de Souza wrote: > From: Kees Cook <keescook@chromium.org> > > BugLink: http://bugs.launchpad.net/bugs/1715636 > > Moving the x86_64 and arm64 PIE base from 0x555555554000 to 0x000100000000 > broke AddressSanitizer. This is a partial revert of: > > eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") > 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") > > The AddressSanitizer tool has hard-coded expectations about where > executable mappings are loaded. > > The motivation for changing the PIE base in the above commits was to > avoid the Stack-Clash CVEs that allowed executable mappings to get too > close to heap and stack. This was mainly a problem on 32-bit, but the > 64-bit bases were moved too, in an effort to proactively protect those > systems (proofs of concept do exist that show 64-bit collisions, but > other recent changes to fix stack accounting and setuid behaviors will > minimize the impact). > > The new 32-bit PIE base is fine for ASan (since it matches the ET_EXEC > base), so only the 64-bit PIE base needs to be reverted to let x86 and > arm64 ASan binaries run again. Future changes to the 64-bit PIE base on > these architectures can be made optional once a more dynamic method for > dealing with AddressSanitizer is found. (e.g. always loading PIE into > the mmap region for marked binaries.) > > Link: http://lkml.kernel.org/r/20170807201542.GA21271@beast > Fixes: eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE") > Fixes: 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB") > Signed-off-by: Kees Cook <keescook@chromium.org> > Reported-by: Kostya Serebryany <kcc@google.com> > Acked-by: Will Deacon <will.deacon@arm.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: <stable@vger.kernel.org> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > (cherry picked from commit c715b72c1ba406f133217b509044c38d8e714a37) > Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> Acked-by: Stefan Bader <stefan.bader@canonical.com> > --- Would be part of 4.4.84 anyway > arch/arm64/include/asm/elf.h | 4 ++-- > arch/x86/include/asm/elf.h | 4 ++-- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h > index 9e11dbe1cec3..329c127e13dc 100644 > --- a/arch/arm64/include/asm/elf.h > +++ b/arch/arm64/include/asm/elf.h > @@ -121,10 +121,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; > > /* > * This is the base location for PIE (ET_DYN with INTERP) loads. On > - * 64-bit, this is raised to 4GB to leave the entire 32-bit address > + * 64-bit, this is above 4GB to leave the entire 32-bit address > * space open for things that want to use the area for 32-bit pointers. > */ > -#define ELF_ET_DYN_BASE 0x100000000UL > +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) > > /* > * When the program starts, a1 contains a pointer to a function to be > diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h > index 07cf288b692e..bcd3d6199464 100644 > --- a/arch/x86/include/asm/elf.h > +++ b/arch/x86/include/asm/elf.h > @@ -247,11 +247,11 @@ extern int force_personality32; > > /* > * This is the base location for PIE (ET_DYN with INTERP) loads. On > - * 64-bit, this is raised to 4GB to leave the entire 32-bit address > + * 64-bit, this is above 4GB to leave the entire 32-bit address > * space open for things that want to use the area for 32-bit pointers. > */ > #define ELF_ET_DYN_BASE (mmap_is_ia32() ? 0x000400000UL : \ > - 0x100000000UL) > + (TASK_SIZE / 3 * 2)) > > /* This yields a mask that user programs can use to figure out what > instruction set this CPU supports. This could be done in user space, >
Applied to xenial/master-next branch. Thanks.
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 9e11dbe1cec3..329c127e13dc 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -121,10 +121,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; /* * This is the base location for PIE (ET_DYN with INTERP) loads. On - * 64-bit, this is raised to 4GB to leave the entire 32-bit address + * 64-bit, this is above 4GB to leave the entire 32-bit address * space open for things that want to use the area for 32-bit pointers. */ -#define ELF_ET_DYN_BASE 0x100000000UL +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) /* * When the program starts, a1 contains a pointer to a function to be diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 07cf288b692e..bcd3d6199464 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -247,11 +247,11 @@ extern int force_personality32; /* * This is the base location for PIE (ET_DYN with INTERP) loads. On - * 64-bit, this is raised to 4GB to leave the entire 32-bit address + * 64-bit, this is above 4GB to leave the entire 32-bit address * space open for things that want to use the area for 32-bit pointers. */ #define ELF_ET_DYN_BASE (mmap_is_ia32() ? 0x000400000UL : \ - 0x100000000UL) + (TASK_SIZE / 3 * 2)) /* This yields a mask that user programs can use to figure out what instruction set this CPU supports. This could be done in user space,