| Message ID | 20191011000609.29728-30-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | vmlinux.lds.h: Refactor EXCEPTION_TABLE and NOTES | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (6edfc6487b474fe01857dc3f1a9cd701bb9b21c8) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | warning | total: 0 errors, 1 warnings, 0 checks, 8 lines checked |
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 = .;
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> --- arch/x86/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)