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kprobes/x86: Check for invalid ftrace location in __recover_probed_insn() 

__recover_probed_insn() should always be called from an address
where an instructions starts. The check for ftrace_location()
might help to discover a potential inconsistency.

This patch adds WARN_ON() when the inconsistency is detected.
Also it adds handling of the situation when the original code
can not get recovered.

Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Cc: Ananth NMavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1424441250-27146-3-git-send-email-pmladek@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Petr Mladek 2015-02-20 15:07:30 +01:00 committed by Ingo Molnar
parent 650b7b23cb
commit 2a6730c8b6
2 changed files with 14 additions and 0 deletions
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12
arch/x86/kernel/kprobes/core.c
View File

@ -227,6 +227,13 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
kp = get_kprobe((void *)addr);
faddr = ftrace_location(addr);
/*
* Addresses inside the ftrace location are refused by
* arch_check_ftrace_location(). Something went terribly wrong
* if such an address is checked here.
*/
if (WARN_ON(faddr && faddr != addr))
return 0UL;
/*
* Use the current code if it is not modified by Kprobe
* and it cannot be modified by ftrace.
@ -265,6 +272,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
* Recover the probed instruction at addr for further analysis.
* Caller must lock kprobes by kprobe_mutex, or disable preemption
* for preventing to release referencing kprobes.
* Returns zero if the instruction can not get recovered.
*/
unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
{
@ -299,6 +307,8 @@ static int can_probe(unsigned long paddr)
* normally used, we just go through if there is no kprobe.
*/
__addr = recover_probed_instruction(buf, addr);
if (!__addr)
return 0;
kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);
insn_get_length(&insn);
@ -347,6 +357,8 @@ int __copy_instruction(u8 *dest, u8 *src)
unsigned long recovered_insn =
recover_probed_instruction(buf, (unsigned long)src);
if (!recovered_insn)
return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
/* Another subsystem puts a breakpoint, failed to recover */

2
arch/x86/kernel/kprobes/opt.c
View File

@ -259,6 +259,8 @@ static int can_optimize(unsigned long paddr)
*/
return 0;
recovered_insn = recover_probed_instruction(buf, addr);
if (!recovered_insn)
return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
/* Another subsystem puts a breakpoint */