Re: [PATCH v2 2/3] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2019-08-21 02:07:48
Also in:
linux-doc, lkml
Hi Jisheng, On Tue, 20 Aug 2019 03:53:31 +0000 Jisheng Zhang [off-list ref] wrote:
For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr correspondingly.
Either KPROBES_ON_FTRACE=y or not, ftrace_location() check must be done correctly. If it failed, kprobes can modify the instruction which can be modified by ftrace.
quoted hunk ↗ jump to hunk
Signed-off-by: Jisheng Zhang <redacted> --- kernel/kprobes.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9873fc627d61..3fd2f68644da 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c@@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) int __weak arch_check_ftrace_location(struct kprobe *p) { - unsigned long ftrace_addr; + unsigned long ftrace_addr, addr = (unsigned long)p->addr; - ftrace_addr = ftrace_location((unsigned long)p->addr); +#ifdef CONFIG_KPROBES_ON_FTRACE + addr = ftrace_call_adjust(addr); +#endif + ftrace_addr = ftrace_location(addr);
No, this is not right way to do. If we always need to adjust address before calling ftrace_location(), something wrong with ftrace_location() interface. ftrace_location(addr) must check the address is within the range which can be changed by ftrace. (dyn->ip <= addr <= dyn->ip+MCOUNT_INSN_SIZE)
if (ftrace_addr) {
#ifdef CONFIG_KPROBES_ON_FTRACE
/* Given address is not on the instruction boundary */
- if ((unsigned long)p->addr != ftrace_addr)
+ if (addr != ftrace_addr)
return -EILSEQ;
p->flags |= KPROBE_FLAG_FTRACE;
+ p->addr = (kprobe_opcode_t *)addr;And again, please don't change the p->addr silently. Thank you,
#else /* !CONFIG_KPROBES_ON_FTRACE */ return -EINVAL; #endif -- 2.23.0.rc1
-- Masami Hiramatsu [off-list ref] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel