From c32fd59314c343db88c3ea4a203870481d33c3d2 Mon Sep 17 00:00:00 2001
From: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Tue, 21 Jan 2025 16:11:06 -0500
Subject: [PATCH] Fix underallocation of abort_msg_s struct (CVE-2025-0395)

Include the space needed to store the length of the message itself, in
addition to the message string.  This resolves BZ #32582.

Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
(cherry picked from commit 68ee0f704cb81e9ad0a78c644a83e1e9cd2ee578)
---
 NEWS                       | 6 ++++++
 assert/assert.c            | 4 +++-
 sysdeps/posix/libc_fatal.c | 4 +++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/assert/assert.c b/assert/assert.c
index b7c7a4a1ba..65a9fedf0d 100644
--- a/assert/assert.c
+++ b/assert/assert.c
@@ -18,6 +18,7 @@
 #include <assert.h>
 #include <atomic.h>
 #include <ldsodefs.h>
+#include <libc-pointer-arith.h>
 #include <libintl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -64,7 +65,8 @@ __assert_fail_base (const char *fmt, const char *assertion, const char *file,
       (void) __fxprintf (NULL, "%s", str);
       (void) fflush (stderr);
 
-      total = (total + 1 + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1);
+      total = ALIGN_UP (total + sizeof (struct abort_msg_s) + 1,
+			GLRO(dl_pagesize));
       struct abort_msg_s *buf = __mmap (NULL, total, PROT_READ | PROT_WRITE,
 					MAP_ANON | MAP_PRIVATE, -1, 0);
       if (__glibc_likely (buf != MAP_FAILED))
diff --git a/sysdeps/posix/libc_fatal.c b/sysdeps/posix/libc_fatal.c
index 70edcc10c1..5b9e4b7918 100644
--- a/sysdeps/posix/libc_fatal.c
+++ b/sysdeps/posix/libc_fatal.c
@@ -20,6 +20,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <ldsodefs.h>
+#include <libc-pointer-arith.h>
 #include <paths.h>
 #include <stdarg.h>
 #include <stdbool.h>
@@ -123,7 +124,8 @@ __libc_message (const char *fmt, ...)
 
       WRITEV_FOR_FATAL (fd, iov, nlist, total);
 
-      total = (total + 1 + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1);
+      total = ALIGN_UP (total + sizeof (struct abort_msg_s) + 1,
+			GLRO(dl_pagesize));
       struct abort_msg_s *buf = __mmap (NULL, total,
 					PROT_READ | PROT_WRITE,
 					MAP_ANON | MAP_PRIVATE, -1, 0);
-- 
2.39.3