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>
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index c3b4b46..4e3d5a96 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -228,6 +228,13 @@
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 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 @@
* 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 @@
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 */
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 7c523bb..3aef248 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -259,6 +259,8 @@
*/
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 */