target/mips: fix possible int overflow

[PATCH] target/mips: fix possible int overflow

Posted by gerben@altlinux.org 2 months, 1 week ago

From: Denis Rastyogin <gerben@altlinux.org>

Fix possible overflow in 1 << (DF_BITS(df) - 2) when DF_BITS(df) 
is 64 by using a 64-bit integer for the shift operation.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Reported-by: Dmitriy Fedin <d.fedin@fobos-nt.ru>
Signed-off-by: Denis Rastyogin <gerben@altlinux.org>
---
 target/mips/tcg/msa_helper.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/target/mips/tcg/msa_helper.c b/target/mips/tcg/msa_helper.c
index 1d40383ca4..5ced3168b4 100644
--- a/target/mips/tcg/msa_helper.c
+++ b/target/mips/tcg/msa_helper.c
@@ -5577,7 +5577,7 @@ static inline int64_t msa_mulr_q_df(uint32_t df, int64_t arg1, int64_t arg2)
 {
     int64_t q_min = DF_MIN_INT(df);
     int64_t q_max = DF_MAX_INT(df);
-    int64_t r_bit = 1 << (DF_BITS(df) - 2);
+    int64_t r_bit = 1LL << (DF_BITS(df) - 2);
 
     if (arg1 == q_min && arg2 == q_min) {
         return q_max;
@@ -5685,7 +5685,7 @@ static inline int64_t msa_maddr_q_df(uint32_t df, int64_t dest, int64_t arg1,
 
     int64_t q_max = DF_MAX_INT(df);
     int64_t q_min = DF_MIN_INT(df);
-    int64_t r_bit = 1 << (DF_BITS(df) - 2);
+    int64_t r_bit = 1LL << (DF_BITS(df) - 2);
 
     q_prod = arg1 * arg2;
     q_ret = ((dest << (DF_BITS(df) - 1)) + q_prod + r_bit) >> (DF_BITS(df) - 1);
@@ -5700,7 +5700,7 @@ static inline int64_t msa_msubr_q_df(uint32_t df, int64_t dest, int64_t arg1,
 
     int64_t q_max = DF_MAX_INT(df);
     int64_t q_min = DF_MIN_INT(df);
-    int64_t r_bit = 1 << (DF_BITS(df) - 2);
+    int64_t r_bit = 1LL << (DF_BITS(df) - 2);
 
     q_prod = arg1 * arg2;
     q_ret = ((dest << (DF_BITS(df) - 1)) - q_prod + r_bit) >> (DF_BITS(df) - 1);
-- 
2.42.2

Re: [PATCH] target/mips: fix possible int overflow

Posted by Peter Maydell 2 months, 1 week ago

On Fri, 24 Jan 2025 at 12:27, <gerben@altlinux.org> wrote:
>
> From: Denis Rastyogin <gerben@altlinux.org>
>
> Fix possible overflow in 1 << (DF_BITS(df) - 2) when DF_BITS(df)
> is 64 by using a 64-bit integer for the shift operation.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Reported-by: Dmitriy Fedin <d.fedin@fobos-nt.ru>
> Signed-off-by: Denis Rastyogin <gerben@altlinux.org>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM