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authorEugene Shatokhin <eugene.shatokhin@rosalab.ru>2015-03-17 19:09:18 +0900
committerIngo Molnar <mingo@kernel.org>2015-03-17 14:00:38 +0100
commitc80e5c0c23ce2282476fdc64c4b5e3d3a40723fd (patch)
tree056afab9efce2ce76166abb5d6ba177d62e0ebb0 /arch/x86/kernel/kprobes
parent107eb964d8c04417e8bce9e9ec2ed61d9261aec6 (diff)
kprobes/x86: Return correct length in __copy_instruction()
On x86-64, __copy_instruction() always returns 0 (error) if the instruction uses %rip-relative addressing. This is because kernel_insn_init() is called the second time for 'insn' instance in such cases and sets all its fields to 0. Because of this, trying to place a kprobe on such instruction will fail, register_kprobe() will return -EINVAL. This patch fixes the problem. Signed-off-by: Eugene Shatokhin <eugene.shatokhin@rosalab.ru> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20150317100918.28349.94654.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/kprobes')
-rw-r--r--arch/x86/kernel/kprobes/core.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 4e3d5a9621fe..03189d86357d 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -354,6 +354,7 @@ int __copy_instruction(u8 *dest, u8 *src)
{
struct insn insn;
kprobe_opcode_t buf[MAX_INSN_SIZE];
+ int length;
unsigned long recovered_insn =
recover_probed_instruction(buf, (unsigned long)src);
@@ -361,16 +362,18 @@ int __copy_instruction(u8 *dest, u8 *src)
return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
+ length = insn.length;
+
/* Another subsystem puts a breakpoint, failed to recover */
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
return 0;
- memcpy(dest, insn.kaddr, insn.length);
+ memcpy(dest, insn.kaddr, length);
#ifdef CONFIG_X86_64
if (insn_rip_relative(&insn)) {
s64 newdisp;
u8 *disp;
- kernel_insn_init(&insn, dest, insn.length);
+ kernel_insn_init(&insn, dest, length);
insn_get_displacement(&insn);
/*
* The copied instruction uses the %rip-relative addressing
@@ -394,7 +397,7 @@ int __copy_instruction(u8 *dest, u8 *src)
*(s32 *) disp = (s32) newdisp;
}
#endif
- return insn.length;
+ return length;
}
static int arch_copy_kprobe(struct kprobe *p)