6.5-stable review patch. If anyone has any objections, please let me know.
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From: Song Liu song@kernel.org
commit 65e710899fd19f435f40268f3a92dfaa11f14470 upstream.
With ":text =0xcccc", ld.lld fills unused text area with 0xcccc0000. Example objdump -D output:
ffffffff82b04203: 00 00 add %al,(%rax) ffffffff82b04205: cc int3 ffffffff82b04206: cc int3 ffffffff82b04207: 00 00 add %al,(%rax) ffffffff82b04209: cc int3 ffffffff82b0420a: cc int3
Replace it with ":text =0xcccccccc", so we get the following instead:
ffffffff82b04203: cc int3 ffffffff82b04204: cc int3 ffffffff82b04205: cc int3 ffffffff82b04206: cc int3 ffffffff82b04207: cc int3 ffffffff82b04208: cc int3
gcc/ld doesn't seem to have the same issue. The generated code stays the same for gcc/ld.
Signed-off-by: Song Liu song@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Kees Cook keescook@chromium.org Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Fixes: 7705dc855797 ("x86/vmlinux: Use INT3 instead of NOP for linker fill bytes") Link: https://lore.kernel.org/r/20230906175215.2236033-1-song@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -156,7 +156,7 @@ SECTIONS ALIGN_ENTRY_TEXT_END *(.gnu.warning)
- } :text =0xcccc + } :text = 0xcccccccc
/* End of text section, which should occupy whole number of pages */ _etext = .;