The following commit has been merged into the core/core branch of tip: Commit-ID: 9fccc5c0c99f238aa1b0460fccbdb30a887e7036 Gitweb: https://git.kernel.org/tip/9fccc5c0c99f238aa1b0460fccbdb30a887e7036 Author: Kees Cook <keescook@xxxxxxxxxxxx> AuthorDate: Thu, 26 Mar 2020 23:48:17 -07:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Mon, 20 Apr 2020 19:24:33 +02:00 x86/elf: Disable automatic READ_IMPLIES_EXEC on 64-bit With modern x86 64-bit environments, there should never be a need for automatic READ_IMPLIES_EXEC, as the architecture is intended to always be execute-bit aware (as in, the default memory protection should be NX unless a region explicitly requests to be executable). There were very old x86_64 systems that lacked the NX bit, but for those, the NX bit is, obviously, unenforceable, so these changes should have no impact on them. Suggested-by: Hector Marco-Gisbert <hecmargi@xxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200327064820.12602-4-keescook@xxxxxxxxxxxx --- arch/x86/include/asm/elf.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 397a1c7..452beed 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -287,7 +287,7 @@ extern u32 elf_hwcap2; * CPU: | lacks NX* | has NX, ia32 | has NX, x86_64 | * ELF: | | | | * ---------------------|------------|------------------|----------------| - * missing PT_GNU_STACK | exec-all | exec-all | exec-all | + * missing PT_GNU_STACK | exec-all | exec-all | exec-none | * PT_GNU_STACK == RWX | exec-stack | exec-stack | exec-stack | * PT_GNU_STACK == RW | exec-none | exec-none | exec-none | * @@ -303,7 +303,7 @@ extern u32 elf_hwcap2; * */ #define elf_read_implies_exec(ex, executable_stack) \ - (executable_stack == EXSTACK_DEFAULT) + (mmap_is_ia32() && executable_stack == EXSTACK_DEFAULT) struct task_struct;
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