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kprobes/x86: Use probe_kernel_read() instead of memcpy() 

Use probe_kernel_read() for avoiding unexpected faults while
copying kernel text in __recover_probed_insn(),
__recover_optprobed_insn() and __copy_instruction().

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.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/149076382624.22469.10091613887942958518.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2017-03-29 14:03:56 +09:00 committed by Ingo Molnar
parent d0381c81c2
commit ea1e34fc36
2 changed files with 13 additions and 4 deletions
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12
arch/x86/kernel/kprobes/core.c
View File

@ -259,7 +259,10 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
* Fortunately, we know that the original code is the ideal 5-byte * Fortunately, we know that the original code is the ideal 5-byte
* long NOP. * long NOP.
*/ */
memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); if (probe_kernel_read(buf, (void *)addr,
MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
return 0UL;
if (faddr) if (faddr)
memcpy(buf, ideal_nops[NOP_ATOMIC5], 5); memcpy(buf, ideal_nops[NOP_ATOMIC5], 5);
else else
@ -271,7 +274,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
* Recover the probed instruction at addr for further analysis. * Recover the probed instruction at addr for further analysis.
* Caller must lock kprobes by kprobe_mutex, or disable preemption * Caller must lock kprobes by kprobe_mutex, or disable preemption
* for preventing to release referencing kprobes. * for preventing to release referencing kprobes.
* Returns zero if the instruction can not get recovered. * Returns zero if the instruction can not get recovered (or access failed).
*/ */
unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
{ {
@ -365,7 +368,10 @@ int __copy_instruction(u8 *dest, u8 *src)
/* Another subsystem puts a breakpoint, failed to recover */ /* Another subsystem puts a breakpoint, failed to recover */
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
return 0; return 0;
memcpy(dest, insn.kaddr, length);
/* This can access kernel text if given address is not recovered */
if (kernel_probe_read(dest, insn.kaddr, length))
return 0;
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
/* Only x86_64 has RIP relative instructions */ /* Only x86_64 has RIP relative instructions */

5
arch/x86/kernel/kprobes/opt.c
View File

@ -65,7 +65,10 @@ unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
* overwritten by jump destination address. In this case, original * overwritten by jump destination address. In this case, original
* bytes must be recovered from op->optinsn.copied_insn buffer. * bytes must be recovered from op->optinsn.copied_insn buffer.
*/ */
memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); if (probe_kernel_read(buf, (void *)addr,
MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
return 0UL;
if (addr == (unsigned long)kp->addr) { if (addr == (unsigned long)kp->addr) {
buf[0] = kp->opcode; buf[0] = kp->opcode;
memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);