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authorKees Cook <keescook@chromium.org>2017-08-18 15:16:31 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-24 17:02:35 -0700
commit240628085effc47e86f51fc3fb37bc0e628f9a85 (patch)
tree6e99a6fe1ac16c8aadb31ad1e1cea38bfea1dff2 /arch
parentcc971fa12bd2dff6c0432c860d784c6cdaf5a04b (diff)
downloadlinux-linaro-stable-240628085effc47e86f51fc3fb37bc0e628f9a85.tar.gz
mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes
commit c715b72c1ba406f133217b509044c38d8e714a37 upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/elf.h4
-rw-r--r--arch/x86/include/asm/elf.h4
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,