Commit c80e5c0c authored by Eugene Shatokhin's avatar Eugene Shatokhin Committed by Ingo Molnar

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: default avatarEugene Shatokhin <eugene.shatokhin@rosalab.ru>
Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20150317100918.28349.94654.stgit@localhost.localdomainSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 107eb964
...@@ -354,6 +354,7 @@ int __copy_instruction(u8 *dest, u8 *src) ...@@ -354,6 +354,7 @@ int __copy_instruction(u8 *dest, u8 *src)
{ {
struct insn insn; struct insn insn;
kprobe_opcode_t buf[MAX_INSN_SIZE]; kprobe_opcode_t buf[MAX_INSN_SIZE];
int length;
unsigned long recovered_insn = unsigned long recovered_insn =
recover_probed_instruction(buf, (unsigned long)src); recover_probed_instruction(buf, (unsigned long)src);
...@@ -361,16 +362,18 @@ int __copy_instruction(u8 *dest, u8 *src) ...@@ -361,16 +362,18 @@ int __copy_instruction(u8 *dest, u8 *src)
return 0; return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn); insn_get_length(&insn);
length = insn.length;
/* Another subsystem puts a breakpoint, failed to recover */ /* Another subsystem puts a breakpoint, failed to recover */
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
return 0; return 0;
memcpy(dest, insn.kaddr, insn.length); memcpy(dest, insn.kaddr, length);
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
if (insn_rip_relative(&insn)) { if (insn_rip_relative(&insn)) {
s64 newdisp; s64 newdisp;
u8 *disp; u8 *disp;
kernel_insn_init(&insn, dest, insn.length); kernel_insn_init(&insn, dest, length);
insn_get_displacement(&insn); insn_get_displacement(&insn);
/* /*
* The copied instruction uses the %rip-relative addressing * The copied instruction uses the %rip-relative addressing
...@@ -394,7 +397,7 @@ int __copy_instruction(u8 *dest, u8 *src) ...@@ -394,7 +397,7 @@ int __copy_instruction(u8 *dest, u8 *src)
*(s32 *) disp = (s32) newdisp; *(s32 *) disp = (s32) newdisp;
} }
#endif #endif
return insn.length; return length;
} }
static int arch_copy_kprobe(struct kprobe *p) static int arch_copy_kprobe(struct kprobe *p)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment