Mesa (main): pan/decode: Avoid undefined behaviour on shift in bits()

[GitLab Mirror]

Module: Mesa
Branch: main
Commit: 04c02418d74703812a39405df14e130c2d6fd098
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=04c02418d74703812a39405df14e130c2d6fd098

Author: Icecream95 <ixn at disroot.org>
Date:   Wed Jul 14 12:47:30 2021 +1200

pan/decode: Avoid undefined behaviour on shift in bits()

v2: Return 0 instead of `word` (Alyssa)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11869>

---

 src/panfrost/lib/decode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/panfrost/lib/decode.c b/src/panfrost/lib/decode.c
index 07366e45072..7a67121a91b 100644
--- a/src/panfrost/lib/decode.c
+++ b/src/panfrost/lib/decode.c
@@ -451,6 +451,9 @@ bits(u32 word, u32 lo, u32 hi)
         if (hi - lo >= 32)
                 return word; // avoid undefined behavior with the shift
 
+        if (lo >= 32)
+                return 0;
+
         return (word >> lo) & ((1 << (hi - lo)) - 1);
 }