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>

diff --git a/assert/assert.c b/assert/assert.c
index db90b8d7ef57ba679ed7b3a77785b3e46abfb26d..d21d76fa62607d2f6a96591447309f2b2aa8772b 100644 (file)
--- 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 eb72a380eb01c9742f35565e4c6dbdbe06e2384b..d90cc6c681af8e91ac6bbbfe9972d9f78c3c26f1 100644 (file)
--- 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);