Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.13 32/36] powerpc/kprobes: Dereference function pointers only if the address does not belong to kernel text | Date | Mon, 6 Nov 2017 10:12:45 +0100 |
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4.13-stable review patch. If anyone has any objections, please let me know.
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From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
commit e6c4dcb308160115287afd87afb63b5684d75a5b upstream.
This makes the changes introduced in commit 83e840c770f2c5 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") to be specific to the kprobe subsystem.
We previously changed ppc_function_entry() to always check the provided address to confirm if it needed to be dereferenced. This is actually only an issue for kprobe blacklisted asm labels (through use of _ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the additional checks are not really necessary for our other uses.
As such, move this check to the kprobes subsystem.
Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/powerpc/kernel/kprobes.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -600,7 +600,12 @@ NOKPROBE_SYMBOL(kprobe_fault_handler); unsigned long arch_deref_entry_point(void *entry) { - return ppc_global_function_entry(entry); +#ifdef PPC64_ELF_ABI_v1 + if (!kernel_text_address((unsigned long)entry)) + return ppc_global_function_entry(entry); + else +#endif + return (unsigned long)entry; } NOKPROBE_SYMBOL(arch_deref_entry_point);
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