Messages in this thread Patch in this message | | | Date | Mon, 7 Jun 2021 10:52:17 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] arm64: ftrace: don't dereference a probably invalid address |
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On Mon, 7 Jun 2021 22:15:22 +0800 Mark-PK Tsai <mark-pk.tsai@mediatek.com> wrote:
> And the crash is becuase kernel trying to read *rec->ip in print_ip_ins() if > ftrace_bug() get error code -EINVAL.
Right, so the actual fix should be something like this:
[ not tested, nor even compiled ]
-- Steve
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2e8a3fde7104..72ef4dccbcc4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1967,12 +1967,18 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, static void print_ip_ins(const char *fmt, const unsigned char *p) { + char ins[MCOUNT_INSN_SIZE]; int i; + if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) { + printk(KERN_CONT "%s[FAULT](%px)", fmt, p); + return; + } + printk(KERN_CONT "%s", fmt); for (i = 0; i < MCOUNT_INSN_SIZE; i++) - printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]); + printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]); } enum ftrace_bug_type ftrace_bug_type;
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