diff options
| -rw-r--r-- | arch/x86/kvm/emulate.c | 43 |
1 files changed, 33 insertions, 10 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 8aa66068712f..52a96270b560 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -641,7 +641,8 @@ static bool insn_aligned(struct x86_emulate_ctxt *ctxt, unsigned size) static int __linearize(struct x86_emulate_ctxt *ctxt, struct segmented_address addr, - unsigned size, bool write, bool fetch, + unsigned *max_size, unsigned size, + bool write, bool fetch, ulong *linear) { struct desc_struct desc; @@ -652,10 +653,15 @@ static int __linearize(struct x86_emulate_ctxt *ctxt, unsigned cpl; la = seg_base(ctxt, addr.seg) + addr.ea; + *max_size = 0; switch (ctxt->mode) { case X86EMUL_MODE_PROT64: if (((signed long)la << 16) >> 16 != la) return emulate_gp(ctxt, 0); + + *max_size = min_t(u64, ~0u, (1ull << 48) - la); + if (size > *max_size) + goto bad; break; default: usable = ctxt->ops->get_segment(ctxt, &sel, &desc, NULL, @@ -673,20 +679,25 @@ static int __linearize(struct x86_emulate_ctxt *ctxt, if ((ctxt->mode == X86EMUL_MODE_REAL) && !fetch && (ctxt->d & NoBigReal)) { /* la is between zero and 0xffff */ - if (la > 0xffff || (u32)(la + size - 1) > 0xffff) + if (la > 0xffff) goto bad; + *max_size = 0x10000 - la; } else if ((desc.type & 8) || !(desc.type & 4)) { /* expand-up segment */ - if (addr.ea > lim || (u32)(addr.ea + size - 1) > lim) + if (addr.ea > lim) goto bad; + *max_size = min_t(u64, ~0u, (u64)lim + 1 - addr.ea); } else { /* expand-down segment */ - if (addr.ea <= lim || (u32)(addr.ea + size - 1) <= lim) + if (addr.ea <= lim) goto bad; lim = desc.d ? 0xffffffff : 0xffff; - if (addr.ea > lim || (u32)(addr.ea + size - 1) > lim) + if (addr.ea > lim) goto bad; + *max_size = min_t(u64, ~0u, (u64)lim + 1 - addr.ea); } + if (size > *max_size) + goto bad; cpl = ctxt->ops->cpl(ctxt); if (!(desc.type & 8)) { /* data segment */ @@ -721,7 +732,8 @@ static int linearize(struct x86_emulate_ctxt *ctxt, unsigned size, bool write, ulong *linear) { - return __linearize(ctxt, addr, size, write, false, linear); + unsigned max_size; + return __linearize(ctxt, addr, &max_size, size, write, false, linear); } @@ -746,17 +758,27 @@ static int segmented_read_std(struct x86_emulate_ctxt *ctxt, static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size) { int rc; - unsigned size; + unsigned size, max_size; unsigned long linear; int cur_size = ctxt->fetch.end - ctxt->fetch.data; struct segmented_address addr = { .seg = VCPU_SREG_CS, .ea = ctxt->eip + cur_size }; - size = 15UL ^ cur_size; - rc = __linearize(ctxt, addr, size, false, true, &linear); + /* + * We do not know exactly how many bytes will be needed, and + * __linearize is expensive, so fetch as much as possible. We + * just have to avoid going beyond the 15 byte limit, the end + * of the segment, or the end of the page. + * + * __linearize is called with size 0 so that it does not do any + * boundary check itself. Instead, we use max_size to check + * against op_size. + */ + rc = __linearize(ctxt, addr, &max_size, 0, false, true, &linear); if (unlikely(rc != X86EMUL_CONTINUE)) return rc; + size = min_t(unsigned, 15UL ^ cur_size, max_size); size = min_t(unsigned, size, PAGE_SIZE - offset_in_page(linear)); /* @@ -766,7 +788,8 @@ static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size) * still, we must have hit the 15-byte boundary. */ if (unlikely(size < op_size)) - return X86EMUL_UNHANDLEABLE; + return emulate_gp(ctxt, 0); + rc = ctxt->ops->fetch(ctxt, linear, ctxt->fetch.end, size, &ctxt->exception); if (unlikely(rc != X86EMUL_CONTINUE)) |