diff options
| author | Kees Cook <keescook@chromium.org> | 2019-10-29 14:13:51 -0700 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-11-04 19:10:08 +0100 |
| commit | 7705dc8557973d8ad8f10840f61d8ec805695e9e (patch) | |
| tree | 56e26e72fbf40763767e493f4bb429222ebd1250 /arch/x86/kernel/vmlinux.lds.S | |
| parent | a329975491aafcb1fb6e2fad0de22cae5c16154f (diff) | |
x86/vmlinux: Use INT3 instead of NOP for linker fill bytes
Instead of using 0x90 (NOP) to fill bytes between functions, which makes
it easier to sloppily target functions in function pointer overwrite
attacks, fill with 0xCC (INT3) to force a trap. Also drop the space
between "=" and the value to better match the binutils documentation
https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html#Output-Section-Fill
Example "objdump -d" before:
...
ffffffff810001e0 <start_cpu0>:
ffffffff810001e0: 48 8b 25 e1 b1 51 01 mov 0x151b1e1(%rip),%rsp # ffffffff8251b3c8 <initial_stack>
ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 <secondary_startup_64+0x91>
ffffffff810001ec: 90 nop
ffffffff810001ed: 90 nop
ffffffff810001ee: 90 nop
ffffffff810001ef: 90 nop
ffffffff810001f0 <__startup_64>:
...
After:
...
ffffffff810001e0 <start_cpu0>:
ffffffff810001e0: 48 8b 25 41 79 53 01 mov 0x1537941(%rip),%rsp # ffffffff82537b28 <initial_stack>
ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 <secondary_startup_64+0x91>
ffffffff810001ec: cc int3
ffffffff810001ed: cc int3
ffffffff810001ee: cc int3
ffffffff810001ef: cc int3
ffffffff810001f0 <__startup_64>:
...
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Ross Zwisler <zwisler@chromium.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-30-keescook@chromium.org
Diffstat (limited to 'arch/x86/kernel/vmlinux.lds.S')
| -rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index b06d6e1188de..3a1a819da137 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -144,7 +144,7 @@ SECTIONS *(.text.__x86.indirect_thunk) __indirect_thunk_end = .; #endif - } :text = 0x9090 + } :text =0xcccc /* End of text section, which should occupy whole number of pages */ _etext = .; |