Commit 77e768ec authored by Borislav Petkov's avatar Borislav Petkov
Browse files

x86/kprobes: Convert to insn_decode() 



Simplify code, improve decoding error checking.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20210304174237.31945-12-bp@alien8.de
parent 1580f488

arch/x86/kernel/kprobes/core.c

+11 −6
Original line number Diff line number Diff line
@@ -265,6 +265,8 @@ static int can_probe(unsigned long paddr) 
	/* Decode instructions */

	addr = paddr - offset;

	while (addr < paddr) {

		int ret;



		/*

		 * Check if the instruction has been modified by another

		 * kprobe, in which case we replace the breakpoint by the
@@ -276,8 +278,10 @@ static int can_probe(unsigned long paddr) 
		__addr = recover_probed_instruction(buf, addr);

		if (!__addr)

			return 0;

		kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);

		insn_get_length(&insn);



		ret = insn_decode(&insn, (void *)__addr, MAX_INSN_SIZE, INSN_MODE_KERN);

		if (ret < 0)

			return 0;



		/*

		 * Another debugging subsystem might insert this breakpoint.
@@ -301,8 +305,8 @@ static int can_probe(unsigned long paddr) 
int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)

{

	kprobe_opcode_t buf[MAX_INSN_SIZE];

	unsigned long recovered_insn =

		recover_probed_instruction(buf, (unsigned long)src);

	unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src);

	int ret;



	if (!recovered_insn || !insn)

		return 0;
@@ -312,8 +316,9 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn) 
			MAX_INSN_SIZE))

		return 0;



	kernel_insn_init(insn, dest, MAX_INSN_SIZE);

	insn_get_length(insn);

	ret = insn_decode(insn, dest, MAX_INSN_SIZE, INSN_MODE_KERN);

	if (ret < 0)

		return 0;



	/* We can not probe force emulate prefixed instruction */

	if (insn_has_emulate_prefix(insn))

arch/x86/kernel/kprobes/opt.c

+7 −2
Original line number Diff line number Diff line
@@ -312,6 +312,8 @@ static int can_optimize(unsigned long paddr) 
	addr = paddr - offset;

	while (addr < paddr - offset + size) { /* Decode until function end */

		unsigned long recovered_insn;

		int ret;



		if (search_exception_tables(addr))

			/*

			 * Since some fixup code will jumps into this function,
@@ -321,8 +323,11 @@ static int can_optimize(unsigned long paddr) 
		recovered_insn = recover_probed_instruction(buf, addr);

		if (!recovered_insn)

			return 0;

		kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);

		insn_get_length(&insn);



		ret = insn_decode(&insn, (void *)recovered_insn, MAX_INSN_SIZE, INSN_MODE_KERN);

		if (ret < 0)

			return 0;



		/*

		 * In the case of detecting unknown breakpoint, this could be

		 * a padding INT3 between functions. Let's check that all the