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authorMichael Ellerman <michael@ellerman.id.au>2007-07-19 04:48:11 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 13:04:44 -0400
commit3d7e33825d8799115dd2495c9944badd3272a623 (patch)
tree869eeefa9dd88c622db199f636cd1785c6099947 /kernel
parent9e367d859297b9377d65574f538cf52730e9eda8 (diff)
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 <michael@ellerman.id.au> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kprobes.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9e47d8c493f3..3e9f513a728d 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -675,9 +675,18 @@ static struct notifier_block kprobe_exceptions_nb = {
675 .priority = 0x7fffffff /* we need to be notified first */ 675 .priority = 0x7fffffff /* we need to be notified first */
676}; 676};
677 677
678unsigned long __weak arch_deref_entry_point(void *entry)
679{
680 return (unsigned long)entry;
681}
678 682
679int __kprobes register_jprobe(struct jprobe *jp) 683int __kprobes register_jprobe(struct jprobe *jp)
680{ 684{
685 unsigned long addr = arch_deref_entry_point(jp->entry);
686
687 if (!kernel_text_address(addr))
688 return -EINVAL;
689
681 /* Todo: Verify probepoint is a function entry point */ 690 /* Todo: Verify probepoint is a function entry point */
682 jp->kp.pre_handler = setjmp_pre_handler; 691 jp->kp.pre_handler = setjmp_pre_handler;
683 jp->kp.break_handler = longjmp_break_handler; 692 jp->kp.break_handler = longjmp_break_handler;