diff options
| author | Eugene Shatokhin <eugene.shatokhin@rosalab.ru> | 2015-03-17 19:09:18 +0900 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-07-30 13:21:24 +0200 |
| commit | b7889b59bcb13c97329f5c639b89bf4673b8ae1c (patch) | |
| tree | 908222268c0d3e7ea0050efe7207e4ba30214431 | |
| parent | 9a8c56f0cd47d1bbf8fcfa3d7750e9345e11463f (diff) | |
| download | lwn-b7889b59bcb13c97329f5c639b89bf4673b8ae1c.tar.gz lwn-b7889b59bcb13c97329f5c639b89bf4673b8ae1c.zip | |
kprobes/x86: Return correct length in __copy_instruction()
commit c80e5c0c23ce2282476fdc64c4b5e3d3a40723fd upstream.
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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index a1f5b1866cbe..490fee15fea5 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -326,13 +326,16 @@ int __kprobes __copy_instruction(u8 *dest, u8 *src) { struct insn insn; kprobe_opcode_t buf[MAX_INSN_SIZE]; + int length; kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src)); 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)) { @@ -362,7 +365,7 @@ int __kprobes __copy_instruction(u8 *dest, u8 *src) *(s32 *) disp = (s32) newdisp; } #endif - return insn.length; + return length; } static int __kprobes arch_copy_kprobe(struct kprobe *p) |