[PULL,20/21] target/sh4: Avoid shift into sign bit in update_itlb_use()

Commit Message

Peter Maydell July 30, 2024, 9:40 a.m. UTC

In update_itlb_use() the variables or_mask and and_mask are uint8_t,
which means that in expressions like "and_mask << 24" the usual C
arithmetic conversions will result in the shift being done as a
signed int type, and so we will shift into the sign bit. For QEMU
this isn't undefined behaviour because we use -fwrapv; but we can
avoid it anyway by using uint32_t types for or_mask and and_mask.

Resolves: Coverity CID 1547628
Signed-off-by: Peter Maydell <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Reviewed-by: Richard Henderson <[e-mail]>
Reviewed-by: Yoshinori Sato <[e-mail]>
Message-id: [e-mail]
---
 target/sh4/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/target/sh4/helper.c b/target/sh4/helper.c
index 67029106277..9659c695504 100644
--- a/target/sh4/helper.c
+++ b/target/sh4/helper.c
@@ -187,7 +187,7 @@  void superh_cpu_do_interrupt(CPUState *cs)
 
 static void update_itlb_use(CPUSH4State * env, int itlbnb)
 {
-    uint8_t or_mask = 0, and_mask = (uint8_t) - 1;
+    uint32_t or_mask = 0, and_mask = 0xff;
 
     switch (itlbnb) {
     case 0: