On Mon, 2018-03-19 at 19:05 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > > [ Upstream commit d0381c81c2f782fa2131178d11e0cfb23d50d631 ] This caused a regression in mainline, fixed by: commit c93f5cf571e7795f97d49ef51b766cf25e328545 Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Date: Thu May 25 19:38:17 2017 +0900 kprobes/x86: Fix to set RWX bits correctly before releasing trampoline Ben. > Set the pages which is used for kprobes' singlestep buffer > and optprobe's trampoline instruction buffer to readonly. > This can prevent unexpected (or unintended) instruction > modification. > > This also passes rodata_test as below. > > Without this patch, rodata_test shows a warning: > > WARNING: CPU: 0 PID: 1 at arch/x86/mm/dump_pagetables.c:235 note_page+0x7a9/0xa20 > x86/mm: Found insecure W+X mapping at address ffffffffa0000000/0xffffffffa0000000 > > With this fix, no W+X pages are found: > > x86/mm: Checked W+X mappings: passed, no W+X pages found. > rodata_test: all tests were successful > > Reported-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxxxxxxxxxx> > Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Cc: Brian Gerst <brgerst@xxxxxxxxx> > Cc: David S . Miller <davem@xxxxxxxxxxxxx> > Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> > Cc: H. Peter Anvin <hpa@xxxxxxxxx> > Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Ye Xiaolong <xiaolong.ye@xxxxxxxxx> > Link: http://lkml.kernel.org/r/149076375592.22469.14174394514338612247.stgit@devbox > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> > Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > arch/x86/kernel/kprobes/core.c | 4 ++++ > arch/x86/kernel/kprobes/opt.c | 3 +++ > 2 files changed, 7 insertions(+) > > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -406,6 +406,8 @@ static int arch_copy_kprobe(struct kprob > { > int ret; > > + set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1); > + > /* Copy an instruction with recovering if other optprobe modifies it.*/ > ret = __copy_instruction(p->ainsn.insn, p->addr); > if (!ret) > @@ -420,6 +422,8 @@ static int arch_copy_kprobe(struct kprob > else > p->ainsn.boostable = -1; > > + set_memory_ro((unsigned long)p->ainsn.insn & PAGE_MASK, 1); > + > /* Check whether the instruction modifies Interrupt Flag or not */ > p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); > > --- a/arch/x86/kernel/kprobes/opt.c > +++ b/arch/x86/kernel/kprobes/opt.c > @@ -370,6 +370,7 @@ int arch_prepare_optimized_kprobe(struct > } > > buf = (u8 *)op->optinsn.insn; > + set_memory_rw((unsigned long)buf & PAGE_MASK, 1); > > /* Copy instructions into the out-of-line buffer */ > ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr); > @@ -392,6 +393,8 @@ int arch_prepare_optimized_kprobe(struct > synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size, > (u8 *)op->kp.addr + op->optinsn.size); > > + set_memory_ro((unsigned long)buf & PAGE_MASK, 1); > + > flush_icache_range((unsigned long) buf, > (unsigned long) buf + TMPL_END_IDX + > op->optinsn.size + RELATIVEJUMP_SIZE); -- Ben Hutchings Software Developer, Codethink Ltd.