__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...@hitachi.com>
Signed-off-by: Petr Mladek <pmla...@suse.cz>
---
arch/x86/kernel/kprobes/core.c | 12 ++++++++++++
arch/x86/kernel/kprobes/opt.c | 2 ++
2 files changed, 14 insertions(+)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 70b9b0c12682..a8e8520b953d 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -228,6 +228,13 @@ __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 */
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 0dd8d089c315..7b3b9d15c47a 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -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 */
--
1.8.5.6
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