From: Borislav Petkov bp@suse.de
[ Upstream commit 77e768ec1391dc0d6cd89822aa60b9a1c1bd8128 ]
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 Stable-dep-of: 63dc6325ff41 ("x86/kprobes: Fix optprobe optimization check with CONFIG_RETHUNK") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/kprobes/core.c | 17 +++++++++++------ arch/x86/kernel/kprobes/opt.c | 9 +++++++-- 2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 97e1d2a9898f..5de757099186 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -293,6 +293,8 @@ 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 @@ -304,8 +306,10 @@ 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;
#ifdef CONFIG_KGDB /* @@ -351,8 +355,8 @@ static int is_IF_modifier(kprobe_opcode_t *insn) 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; @@ -362,8 +366,9 @@ 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)) diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 08eb23074f92..4299fc865732 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -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