4.9-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit d0381c81c2f782fa2131178d11e0cfb23d50d631 ]
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@virtuozzo.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: Ananth N Mavinakayanahalli ananth@linux.vnet.ibm.com Cc: Anil S Keshavamurthy anil.s.keshavamurthy@intel.com Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: David S . Miller davem@davemloft.net Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Ye Xiaolong xiaolong.ye@intel.com Link: http://lkml.kernel.org/r/149076375592.22469.14174394514338612247.stgit@devbo... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -409,6 +409,8 @@ 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) @@ -423,6 +425,8 @@ 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 @@ -371,6 +371,7 @@ 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); @@ -393,6 +394,8 @@ 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);