Allow to ask for deeper callers for leak reports using malloc options.

ok deraadt@

2 files changed, 37 insertions, 4 deletions

diff --git a/src/lib/libc/stdlib/malloc.3 b/src/lib/libc/stdlib/malloc.3
index d893626051..855f217c27 100644
--- a/src/lib/libc/stdlib/malloc.3
+++ b/src/lib/libc/stdlib/malloc.3
@@ -30,9 +30,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     $OpenBSD: malloc.3,v 1.133 2023/06/04 06:58:33 otto Exp $
+.\"     $OpenBSD: malloc.3,v 1.134 2023/06/22 11:04:16 otto Exp $
 .\"
-.Dd $Mdocdate: June 4 2023 $
+.Dd $Mdocdate: June 22 2023 $
 .Dt MALLOC 3
 .Os
 .Sh NAME
@@ -294,6 +294,17 @@ To record the dump:
 To view the leak report:
 .Pp
 .Dl $ kdump -u malloc ...
+.Pp
+By default, the immediate caller of a
+.Nm
+function will be recorded.
+Use malloc options
+.Cm 2
+or
+.Cm 3
+to record the caller one or two stack frames deeper instead.
+These malloc options imply
+.Cm D .
 .It Cm F
 .Dq Freecheck .
 Enable more extensive double free and use after free detection.
@@ -813,3 +824,14 @@ and
 .Fn realloc
 to avoid these problems on
 .Ox .
+.Pp
+The mechanism to record caller functions when using malloc options
+.Cm 2
+or
+.Cm 3
+is not guaranteed to work for all platforms, compilers or compilation
+options,
+and might even crash your program.
+Use
+.Em only
+for debugging purposes.
diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index 04f211c4ef..7bc660525b 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: malloc.c,v 1.286 2023/06/07 12:56:22 aoyama Exp $     */
+/*      $OpenBSD: malloc.c,v 1.287 2023/06/22 11:04:16 otto Exp $       */
 /*
  * Copyright (c) 2008, 2010, 2011, 2016, 2023 Otto Moerbeek <otto@drijf.net>
  * Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
@@ -255,7 +255,11 @@ void malloc_dump(void);
 PROTO_NORMAL(malloc_dump);
 static void malloc_exit(void);
 #endif
-#define CALLER  (DO_STATS ? __builtin_return_address(0) : NULL)
+#define CALLER  ( \
+        DO_STATS == 0 ? NULL : (__builtin_extract_return_addr( \
+        DO_STATS == 1 ? __builtin_return_address(0) : \
+        DO_STATS == 2 ? __builtin_return_address(1) : \
+        DO_STATS == 3 ? __builtin_return_address(2) : NULL)))
 
 /* low bits of r->p determine size: 0 means >= page size and r->size holding
  * real size, otherwise low bits is the bucket + 1
@@ -365,8 +369,15 @@ omalloc_parseopt(char opt)
                 mopts.malloc_stats = 0;
                 break;
         case 'D':
+        case '1':
                 mopts.malloc_stats = 1;
                 break;
+        case '2':
+                mopts.malloc_stats = 2;
+                break;
+        case '3':
+                mopts.malloc_stats = 3;
+                break;
 #endif /* MALLOC_STATS */
         case 'f':
                 mopts.malloc_freecheck = 0;