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

Message ID 20240730094020.2758637-21-peter.maydell@linaro.org
State Accepted
Commit 525650cd71104c046e4260b5acaeb275f520d5c0
Headers show
Series [PULL,01/21] hw/char/bcm2835_aux: Fix assert when receive FIFO fills up | expand

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 <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Message-id: 20240723172431.1757296-1-peter.maydell@linaro.org
---
 target/sh4/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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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: