[FFmpeg-devel] [PATCH 4/5] lavu/intmath.h: Fix UB in ff_ctz_c() and ff_ctzll_c()

["Tomas Härdin" <git@haerdin.se>]

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From f9a12089bc98dde0ccc2487d1442ec6ddb7705f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <git@haerdin.se>
Date: Thu, 16 May 2024 18:10:58 +0200
Subject: [PATCH 4/5] lavu/intmath.h: Fix UB in ff_ctz_c() and ff_ctzll_c()

Found by value analysis
---
 libavutil/intmath.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavutil/intmath.h b/libavutil/intmath.h
index c54d23b7bf..52e11a8d5f 100644
--- a/libavutil/intmath.h
+++ b/libavutil/intmath.h
@@ -119,7 +119,7 @@ static av_always_inline av_const int ff_ctz_c(int v)
         0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
         31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
     };
-    return debruijn_ctz32[(uint32_t)((v & -v) * 0x077CB531U) >> 27];
+    return debruijn_ctz32[(uint32_t)((v & -(uint32_t)v) * 0x077CB531U) >> 27];
 }
 #endif
 
@@ -135,7 +135,7 @@ static av_always_inline av_const int ff_ctzll_c(long long v)
         63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
         51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
     };
-    return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386DU) >> 58];
+    return debruijn_ctz64[(uint64_t)((v & -(uint64_t)v) * 0x022FDD63CC95386DU) >> 58];
 }
 #endif
 
-- 
2.39.2


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