[PULL 05/21] target/s390x: Fix MVCRL with a large value in R0

Thomas Huth posted 21 patches 2 years, 7 months ago
Maintainers: "Alex Bennée" <alex.bennee@linaro.org>, "Daniel P. Berrangé" <berrange@redhat.com>, Thomas Huth <thuth@redhat.com>, Markus Armbruster <armbru@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Juan Quintela <quintela@redhat.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Richard Henderson <richard.henderson@linaro.org>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Matthew Rosato <mjrosato@linux.ibm.com>, Laurent Vivier <laurent@vivier.eu>, Paolo Bonzini <pbonzini@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Peter Xu <peterx@redhat.com>, Leonardo Bras <leobras@redhat.com>
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[PULL 05/21] target/s390x: Fix MVCRL with a large value in R0
Posted by Thomas Huth 2 years, 7 months ago
From: Ilya Leoshkevich <iii@linux.ibm.com>

Using a large R0 causes an assertion error:

    qemu-s390x: target/s390x/tcg/mem_helper.c:183: access_prepare_nf: Assertion `size > 0 && size <= 4096' failed.

Even though PoP explicitly advises against using more than 8 bits for the
size, an emulator crash is never a good thing.

Fix by truncating the size to 8 bits.

Fixes: ea0a1053e276 ("s390x/tcg: Implement Miscellaneous-Instruction-Extensions Facility 3 for the s390x")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: qemu-stable@nongnu.org
Message-Id: <20230704081506.276055-5-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 target/s390x/tcg/mem_helper.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index d02ec861d8..84ad85212c 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -514,6 +514,7 @@ void HELPER(mvcrl)(CPUS390XState *env, uint64_t l, uint64_t dest, uint64_t src)
     int32_t i;
 
     /* MVCRL always copies one more byte than specified - maximum is 256 */
+    l &= 0xff;
     l++;
 
     access_prepare(&srca, env, src, l, MMU_DATA_LOAD, mmu_idx, ra);
-- 
2.39.3