From a07f133e5b6be3881ce0beacc3333629b0d9dbd8 Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Sun, 16 Dec 2018 22:29:29 -0500
Subject: [PATCH] KPath: Prevent setting a KPath to itself causing
 use-after-free.

SetTo frees the buffer before setting it to the new one,
but if KPath sets itself to ... itself, then it will of course
try to access the buffer again.

Spotted by clang-analyzer (amidst quite a few false positives,
so this doesn't seem like an especially good rabbit hole
to go down right now.)
---
 src/system/kernel/fs/KPath.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/system/kernel/fs/KPath.cpp b/src/system/kernel/fs/KPath.cpp
index 3debfbf38f..e0a70bbc72 100644
--- a/src/system/kernel/fs/KPath.cpp
+++ b/src/system/kernel/fs/KPath.cpp
@@ -356,6 +356,9 @@ KPath::Normalize(bool traverseLeafLink)
 KPath&
 KPath::operator=(const KPath& other)
 {
+	if (other.fBuffer == fBuffer)
+		return *this;
+
 	SetTo(other.fBuffer, fLazy ? KPath::LAZY_ALLOC : KPath::DEFAULT,
 		other.fBufferSize);
 	return *this;