+ scripts-sorttable-fix-orc_sort_cmp-to-maintain-symmetry-and-transitivity.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: scripts/sorttable: fix orc_sort_cmp() to maintain symmetry and transitivity
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     scripts-sorttable-fix-orc_sort_cmp-to-maintain-symmetry-and-transitivity.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/scripts-sorttable-fix-orc_sort_cmp-to-maintain-symmetry-and-transitivity.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Kuan-Wei Chiu <visitorckw@gmail.com>
Subject: scripts/sorttable: fix orc_sort_cmp() to maintain symmetry and transitivity
Date: Thu, 26 Dec 2024 22:03:32 +0800

The orc_sort_cmp() function, used with qsort(), previously violated the
symmetry and transitivity rules required by the C standard.  Specifically,
when both entries are ORC_TYPE_UNDEFINED, it could result in both a < b
and b < a, which breaks the required symmetry and transitivity.  This can
lead to undefined behavior and incorrect sorting results, potentially
causing memory corruption in glibc implementations [1].

Symmetry: If x < y, then y > x.
Transitivity: If x < y and y < z, then x < z.

Fix the comparison logic to return 0 when both entries are
ORC_TYPE_UNDEFINED, ensuring compliance with qsort() requirements.

Link: https://www.qualys.com/2024/01/30/qsort.txt [1]
Link: https://lkml.kernel.org/r/20241226140332.2670689-1-visitorckw@gmail.com
Fixes: 57fa18994285 ("scripts/sorttable: Implement build-time ORC unwind table sorting")
Fixes: fb799447ae29 ("x86,objtool: Split UNWIND_HINT_EMPTY in two")
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: <chuang@cs.nycu.edu.tw>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 scripts/sorttable.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/scripts/sorttable.h~scripts-sorttable-fix-orc_sort_cmp-to-maintain-symmetry-and-transitivity
+++ a/scripts/sorttable.h
@@ -110,7 +110,7 @@ static inline unsigned long orc_ip(const
 
 static int orc_sort_cmp(const void *_a, const void *_b)
 {
-	struct orc_entry *orc_a;
+	struct orc_entry *orc_a, *orc_b;
 	const int *a = g_orc_ip_table + *(int *)_a;
 	const int *b = g_orc_ip_table + *(int *)_b;
 	unsigned long a_val = orc_ip(a);
@@ -128,6 +128,9 @@ static int orc_sort_cmp(const void *_a,
 	 * whitelisted .o files which didn't get objtool generation.
 	 */
 	orc_a = g_orc_table + (a - g_orc_ip_table);
+	orc_b = g_orc_table + (b - g_orc_ip_table);
+	if (orc_a->type == ORC_TYPE_UNDEFINED && orc_b->type == ORC_TYPE_UNDEFINED)
+		return 0;
 	return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
 }
 
_

Patches currently in -mm which might be from visitorckw@gmail.com are

scripts-sorttable-fix-orc_sort_cmp-to-maintain-symmetry-and-transitivity.patch
lib-min_heap-improve-type-safety-in-min_heap-macros-by-using-container_of.patch
lib-test_min_heap-use-inline-min-heap-variants-to-reduce-attack-vector.patch
lib-min_heap-add-brief-introduction-to-min-heap-api.patch
documentation-core-api-min_heap-add-author-information.patch