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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [asan][win] Interceptor failures on Windows Insider builds"
href="https://bugs.llvm.org/show_bug.cgi?id=48677">48677</a>
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<th>Summary</th>
<td>[asan][win] Interceptor failures on Windows Insider builds
</td>
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<th>Product</th>
<td>compiler-rt
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>asan
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>dmajor@mozilla.com
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<th>CC</th>
<td>hans@chromium.org, llvm-bugs@lists.llvm.org, nicolasweber@gmx.de, rnk@google.com
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<p>
<div>
<pre>In newer Windows Insider builds (20277 to 20231 at least), various system
functions are no longer preceded by sufficient `int 3` padding to insert a
hotpatch.
This leads to two problems:
1. ASan falls back to using trampolines, which means it needs to scan through
more instructions than before, so it starts seeing encodings that
`GetInstructionSize()` doesn't know about.
That's easy enough to fix, but then...
2. The increased length of trampolines means a higher risk of clobbering a
branch target. In particular, a later part of `ntdll!strrchr` contains a jump
back to the +3 offset, which is now garbage.</pre>
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