[PATCH 1/2] Fix underallocation of abort_msg_s struct (CVE-2025-0395)

[Siddhesh Poyarekar]

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>
---
 assert/assert.c            | 4 +++-
 sysdeps/posix/libc_fatal.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/assert/assert.c b/assert/assert.c
index db90b8d7ef..d21d76fa62 100644
--- a/assert/assert.c
+++ b/assert/assert.c
@@ -17,6 +17,7 @@
 
 #include <intprops.h>
 #include <ldsodefs.h>
+#include <libc-pointer-arith.h>
 #include <libintl.h>
 #include <libio/iolibio.h>
 #include <setvmaname.h>
@@ -60,7 +61,8 @@ __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 eb72a380eb..d90cc6c681 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>
@@ -105,7 +106,8 @@ __libc_message_impl (const char *fmt, ...)
     {
       WRITEV_FOR_FATAL (fd, iov, iovcnt, 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);
-- 
2.47.1