This fixes the bug: 'user-to-root privesc inside VM via bad translation
caching' reported by Jann Horn here:
https://bugs.chromium.org/p/project-zero/issues/detail?id=1122
CC: Richard Henderson <r...@twiddle.net>
CC: Peter Maydell <peter.mayd...@linaro.org>
CC: Paolo Bonzini <paolo.bonz...@redhat.com>
Reported-by: Jann Horn <ja...@google.com>
Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
---
target/i386/translate.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/target/i386/translate.c b/target/i386/translate.c
index 72c1b03a2a..1d1372fb43 100644
--- a/target/i386/translate.c
+++ b/target/i386/translate.c
@@ -4418,6 +4418,13 @@ static target_ulong disas_insn(CPUX86State *env,
DisasContext *s,
s->vex_l = 0;
s->vex_v = 0;
next_byte:
+ /* x86 has an upper limit of 15 bytes for an instruction. Since we
+ * do not want to decode and generate IR for an illegal
+ * instruction, the following check limits the instruction size to
+ * 25 bytes: 14 prefix + 1 opc + 6 (modrm+sib+ofs) + 4 imm */
+ if (s->pc - pc_start > 14) {
+ goto illegal_op;
+ }
b = cpu_ldub_code(env, s->pc);
s->pc++;
/* Collect prefixes. */
--
2.11.0
