From df2833b318ee1d8bac8253bb3f7d3b65d6cb72aa Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 8 Jun 2026 08:09:10 +1000
Subject: [PATCH] io: drop the dead/unnecessary read_varint UBSan guard

The cherry-picked #428 wrapped no_sanitize attributes on read_varint() and
read_varlong() in `#ifndef CAREFUL_ALIGNMENT`, but byteorder.h always
#defines CAREFUL_ALIGNMENT (to 0 or 1), so that guard is never true and the
attributes were dead code.

They are also unnecessary: both functions read the assembled value through
an aligned union member (union { char b[5]; int32 x; }), not an unaligned
cast, so UBSan's alignment check never fires there (verified: the ASan+UBSan
suite is clean without them).  Remove the whole block rather than fix the
guard.  (The byteorder.h annotations from #428, which are real and correctly
placed inside the !CAREFUL_ALIGNMENT branch, are kept.)
---
 io.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/io.c b/io.c
index 8d240e44..0b96c270 100644
--- a/io.c
+++ b/io.c
@@ -1813,13 +1813,6 @@ uint32 read_uint(int f)
 	return IVAL(b, 0);
 }
 
-#ifndef CAREFUL_ALIGNMENT
-#ifdef __clang__
-__attribute__((no_sanitize("undefined")))
-#elif GCC_VERSION >= 409
-__attribute__((no_sanitize_undefined))
-#endif
-#endif
 int32 read_varint(int f)
 {
 	union {
@@ -1852,13 +1845,6 @@ int32 read_varint(int f)
 	return u.x;
 }
 
-#ifndef CAREFUL_ALIGNMENT
-#ifdef __clang__
-__attribute__((no_sanitize("undefined")))
-#elif GCC_VERSION >= 409
-__attribute__((no_sanitize_undefined))
-#endif
-#endif
 int64 read_varlong(int f, uchar min_bytes)
 {
 	union {