From 3d7e33825d8799115dd2495c9944badd3272a623 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 19 Jul 2007 01:48:11 -0700 Subject: jprobes: make jprobes a little safer for users I realise jprobes are a razor-blades-included type of interface, but that doesn't mean we can't try and make them safer to use. This guy I know once wrote code like this: struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" }; And then his kernel exploded. Oops. This patch adds an arch hook, arch_deref_entry_point() (I don't like it either) which takes the void * in a struct jprobe, and gives back the text address that it represents. We can then use that in register_jprobe() to check that the entry point we're passed is actually in the kernel text, rather than just some random value. Signed-off-by: Michael Ellerman Cc: Prasanna S Panchamukhi Acked-by: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: David S. Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kprobes.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9e47d8c..3e9f513 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -675,9 +675,18 @@ static struct notifier_block kprobe_exceptions_nb = { .priority = 0x7fffffff /* we need to be notified first */ }; +unsigned long __weak arch_deref_entry_point(void *entry) +{ + return (unsigned long)entry; +} int __kprobes register_jprobe(struct jprobe *jp) { + unsigned long addr = arch_deref_entry_point(jp->entry); + + if (!kernel_text_address(addr)) + return -EINVAL; + /* Todo: Verify probepoint is a function entry point */ jp->kp.pre_handler = setjmp_pre_handler; jp->kp.break_handler = longjmp_break_handler; -- cgit v1.1