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x86/kprobes: Convert to insn_decode() 

Simplify code, improve decoding error checking.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20210304174237.31945-12-bp@alien8.de
This commit is contained in:
Borislav Petkov 2020-11-16 18:10:11 +01:00
parent 1580f488ea
commit 77e768ec13
2 changed files with 18 additions and 8 deletions
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17
arch/x86/kernel/kprobes/core.c
View File

@ -265,6 +265,8 @@ static int can_probe(unsigned long paddr)
/* Decode instructions */ /* Decode instructions */
addr = paddr - offset; addr = paddr - offset;
while (addr < paddr) { while (addr < paddr) {
int ret;
/* /*
* Check if the instruction has been modified by another * Check if the instruction has been modified by another
* kprobe, in which case we replace the breakpoint by the * 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); __addr = recover_probed_instruction(buf, addr);
if (!__addr) if (!__addr)
return 0; 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. * 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) int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
{ {
kprobe_opcode_t buf[MAX_INSN_SIZE]; kprobe_opcode_t buf[MAX_INSN_SIZE];
unsigned long recovered_insn = unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src);
recover_probed_instruction(buf, (unsigned long)src); int ret;
if (!recovered_insn || !insn) if (!recovered_insn || !insn)
return 0; return 0;
@ -312,8 +316,9 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
MAX_INSN_SIZE)) MAX_INSN_SIZE))
return 0; return 0;
kernel_insn_init(insn, dest, MAX_INSN_SIZE); ret = insn_decode(insn, dest, MAX_INSN_SIZE, INSN_MODE_KERN);
insn_get_length(insn); if (ret < 0)
return 0;
/* We can not probe force emulate prefixed instruction */ /* We can not probe force emulate prefixed instruction */
if (insn_has_emulate_prefix(insn)) if (insn_has_emulate_prefix(insn))

9
arch/x86/kernel/kprobes/opt.c
View File

@ -312,6 +312,8 @@ static int can_optimize(unsigned long paddr)
addr = paddr - offset; addr = paddr - offset;
while (addr < paddr - offset + size) { /* Decode until function end */ while (addr < paddr - offset + size) { /* Decode until function end */
unsigned long recovered_insn; unsigned long recovered_insn;
int ret;
if (search_exception_tables(addr)) if (search_exception_tables(addr))
/* /*
* Since some fixup code will jumps into this function, * 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); recovered_insn = recover_probed_instruction(buf, addr);
if (!recovered_insn) if (!recovered_insn)
return 0; 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 * In the case of detecting unknown breakpoint, this could be
* a padding INT3 between functions. Let's check that all the * a padding INT3 between functions. Let's check that all the