From: Neil Schemenauer <nas-github@arctrix.com>
Date: Thu, 21 Oct 2021 13:38:36 +0000 (-0700)
Subject: bpo-45521: Fix a bug in the obmalloc radix tree code. (GH-29051)
X-Git-Tag: v3.11.0a2~118
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=311910b31a4bd94dc79298388b7cb65ca5546438;p=thirdparty%2FPython%2Fcpython.git

bpo-45521: Fix a bug in the obmalloc radix tree code. (GH-29051)

MAP_BOT_LENGTH was incorrectly used to compute MAP_TOP_MASK instead of
MAP_TOP_LENGTH. On 64-bit machines, the error causes the tree to hold
46-bits of virtual addresses, rather than the intended 48-bits.
---

diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-10-18-22-40-33.bpo-45521.GdMiuW.rst b/Misc/NEWS.d/next/Core and Builtins/2021-10-18-22-40-33.bpo-45521.GdMiuW.rst
new file mode 100644
index 000000000000..3a082a4ffdbc
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-10-18-22-40-33.bpo-45521.GdMiuW.rst	
@@ -0,0 +1,3 @@
+Fix a bug in the obmalloc radix tree code.  On 64-bit machines, the bug
+causes the tree to hold 46-bits of virtual addresses, rather than the
+intended 48-bits.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index d8d6f6dea0d5..2eddb2cafd49 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -1341,7 +1341,7 @@ _Py_GetAllocatedBlocks(void)
 
 #define MAP_TOP_BITS INTERIOR_BITS
 #define MAP_TOP_LENGTH (1 << MAP_TOP_BITS)
-#define MAP_TOP_MASK (MAP_BOT_LENGTH - 1)
+#define MAP_TOP_MASK (MAP_TOP_LENGTH - 1)
 
 #define MAP_MID_BITS INTERIOR_BITS
 #define MAP_MID_LENGTH (1 << MAP_MID_BITS)