From 6e8c83d2a3afbfd5ee019ec720b75a42df515caa Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 19 Nov 2020 19:20:18 +0100 Subject: x86/insn-eval: Handle return values from the decoder Now that the different instruction-inspecting functions return a value, test that and return early from callers if error has been encountered. While at it, do not call insn_get_modrm() when calling insn_get_displacement() because latter will make sure to call insn_get_modrm() if ModRM hasn't been parsed yet. Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210304174237.31945-6-bp@alien8.de --- arch/x86/lib/insn-eval.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) (limited to 'arch/x86/lib/insn-eval.c') diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 422a592b6338..321a1579bb66 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -924,10 +924,11 @@ static int get_seg_base_limit(struct insn *insn, struct pt_regs *regs, static int get_eff_addr_reg(struct insn *insn, struct pt_regs *regs, int *regoff, long *eff_addr) { - insn_get_modrm(insn); + int ret; - if (!insn->modrm.nbytes) - return -EINVAL; + ret = insn_get_modrm(insn); + if (ret) + return ret; if (X86_MODRM_MOD(insn->modrm.value) != 3) return -EINVAL; @@ -973,14 +974,14 @@ static int get_eff_addr_modrm(struct insn *insn, struct pt_regs *regs, int *regoff, long *eff_addr) { long tmp; + int ret; if (insn->addr_bytes != 8 && insn->addr_bytes != 4) return -EINVAL; - insn_get_modrm(insn); - - if (!insn->modrm.nbytes) - return -EINVAL; + ret = insn_get_modrm(insn); + if (ret) + return ret; if (X86_MODRM_MOD(insn->modrm.value) > 2) return -EINVAL; @@ -1102,18 +1103,21 @@ static int get_eff_addr_modrm_16(struct insn *insn, struct pt_regs *regs, * @base_offset will have a register, as an offset from the base of pt_regs, * that can be used to resolve the associated segment. * - * -EINVAL on error. + * Negative value on error. */ static int get_eff_addr_sib(struct insn *insn, struct pt_regs *regs, int *base_offset, long *eff_addr) { long base, indx; int indx_offset; + int ret; if (insn->addr_bytes != 8 && insn->addr_bytes != 4) return -EINVAL; - insn_get_modrm(insn); + ret = insn_get_modrm(insn); + if (ret) + return ret; if (!insn->modrm.nbytes) return -EINVAL; @@ -1121,7 +1125,9 @@ static int get_eff_addr_sib(struct insn *insn, struct pt_regs *regs, if (X86_MODRM_MOD(insn->modrm.value) > 2) return -EINVAL; - insn_get_sib(insn); + ret = insn_get_sib(insn); + if (ret) + return ret; if (!insn->sib.nbytes) return -EINVAL; @@ -1190,8 +1196,8 @@ static void __user *get_addr_ref_16(struct insn *insn, struct pt_regs *regs) short eff_addr; long tmp; - insn_get_modrm(insn); - insn_get_displacement(insn); + if (insn_get_displacement(insn)) + goto out; if (insn->addr_bytes != 2) goto out; @@ -1525,7 +1531,9 @@ bool insn_decode_from_regs(struct insn *insn, struct pt_regs *regs, insn->addr_bytes = INSN_CODE_SEG_ADDR_SZ(seg_defs); insn->opnd_bytes = INSN_CODE_SEG_OPND_SZ(seg_defs); - insn_get_length(insn); + if (insn_get_length(insn)) + return false; + if (buf_size < insn->length) return false; -- cgit v1.2.3