x86, mtest2make changes for QEMU 10.2

[PULL 04/10] target/i386/tcg: validate segment registers

Paolo Bonzini posted 10 patches 2 months, 3 weeks ago

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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, Thomas Huth <thuth@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Wei Liu <wei.liu@kernel.org>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>

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[PULL 04/10] target/i386/tcg: validate segment registers

Posted by Paolo Bonzini 2 months, 3 weeks ago

Correctly reject invalid segment registers, including CS when used as
the destination of a MOV.  Ignore the REX prefix as well.

Fixes: 5e9e21bcc4d ("target/i386: move 60-BF opcodes to new decoder", 2024-05-07)
Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3195
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/decode-new.c.inc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/target/i386/tcg/decode-new.c.inc b/target/i386/tcg/decode-new.c.inc
index 805cfd08e83..0f8c5d16938 100644
--- a/target/i386/tcg/decode-new.c.inc
+++ b/target/i386/tcg/decode-new.c.inc
@@ -2059,7 +2059,12 @@ static bool decode_op(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode,
 
     case X86_TYPE_S:  /* reg selects a segment register */
         op->unit = X86_OP_SEG;
-        goto get_reg;
+        op->n = (get_modrm(s, env) >> 3) & 7;
+        /* Values outside [CDEFGS]S, as well as storing to CS, are invalid.  */
+        if (op->n >= 6 || (op->n == R_CS && op == &decode->op[0])) {
+            return false;
+        }
+        break;
 
     case X86_TYPE_P:
         op->unit = X86_OP_MMX;
-- 
2.51.1