Subject: [PATCH v2] gnu: elfutils: Fix cross-compilation.

From: Zheng Junjie <[email-masked]>
Date: Thu, 5 Dec 2024 01:04:21 +0800

* gnu/packages/elf.scm (elfutils): Fix cross-compilation
[arguments]: When cross-compilation, apply patch.
[native-inputs]: When cross-compilation, add patch.
* gnu/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch:
New file.
* gnu/local.mk (dist_patch_DATA): Register it.

Change-Id: Ia1ab9c09124a140608bda34bf62f0ae80eb44f9b
---
 gnu/local.mk                                  |   1 +
 gnu/packages/elf.scm                          |  21 +++-
 ...reading-of-ar_size-in-elf_begin_rand.patch | 116 ++++++++++++++++++
 3 files changed, 136 insertions(+), 2 deletions(-)
 create mode 100644 gnu/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index a7bd32453b0..eee768615ea 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1177,6 +1177,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/eigen-fix-strict-aliasing-bug.patch	\
   %D%/packages/patches/einstein-build.patch			\
   %D%/packages/patches/elfutils-tests-ptrace.patch		\
+  %D%/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch \
   %D%/packages/patches/elixir-path-length.patch			\
   %D%/packages/patches/elm-ghc9.2.patch	\
   %D%/packages/patches/elm-offline-package-registry.patch	\
diff --git a/gnu/packages/elf.scm b/gnu/packages/elf.scm
index 81a753a4835..4fae3929ba2 100644
--- a/gnu/packages/elf.scm
+++ b/gnu/packages/elf.scm
@@ -11,6 +11,7 @@
 ;;; Copyright © 2021 Leo Le Bouter <[email-masked]>
 ;;; Copyright © 2021 Maxime Devos <[email-masked]>
 ;;; Copyright © 2023, 2024 Janneke Nieuwenhuizen <[email-masked]>
+;;; Copyright © 2024 Zheng Junjie <[email-masked]>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -140,9 +141,25 @@ (define-public elfutils
                                   "tests/run-varlocs.sh")
                                (("^#!.*" all)
                                 (string-append all "exit 77;\n"))))))
-             '()))))
+             '())
+         ,@(if
+            (%current-target-system)
+            '((add-after 'unpack 'patch
+                (lambda* (#:key native-inputs #:allow-other-keys)
+                  (invoke "patch" "-Np1" "-i"
+                          (assoc-ref native-inputs
+                                     "elfutils-libdwfl-Rewrite-reading-of-ar\
+_size-in-elf_begin_rand.patch")))))
+            '()))))
 
-    (native-inputs (list m4))
+    (native-inputs
+     (if
+      (%current-target-system)
+      `(("m4" ,m4)
+        ("elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch"
+         ,(search-patch
+           "elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch")))
+      (list m4)))
     (inputs (list xz zlib))
     (home-page "https://sourceware.org/elfutils/")
     (synopsis "Collection of utilities and libraries to handle ELF files and
diff --git a/gnu/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch b/gnu/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch
new file mode 100644
index 00000000000..e9d51359c4b
--- /dev/null
+++ b/gnu/packages/patches/elfutils-libdwfl-Rewrite-reading-of-ar_size-in-elf_begin_rand.patch
@@ -0,0 +1,116 @@
+from https://sourceware.org/cgit/elfutils/patch/?id=0873ae782d14e672e8344775e76b7fca0a8b41bf
+
+Adjust the changelog so it can be applied on elfutils 0.187.
+
+From 0873ae782d14e672e8344775e76b7fca0a8b41bf Mon Sep 17 00:00:00 2001
+From: Mark Wielaard <[email-masked]>
+Date: Thu, 28 Jul 2022 15:31:12 +0200
+Subject: libdwfl: Rewrite reading of ar_size in elf_begin_rand
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+With GCC 12.1.1, glibc 2.35, -fsanitize=undefined and
+-D_FORTIFY_SOURCE=3 we get the following error message:
+
+In file included from /usr/include/ar.h:22,
+                 from ../libelf/libelfP.h:33,
+                 from core-file.c:31:
+In function ‘pread’,
+    inlined from ‘pread_retry’ at ../lib/system.h:188:21,
+    inlined from ‘elf_begin_rand’ at core-file.c:86:16,
+    inlined from ‘core_file_read_eagerly’ at core-file.c:205:15:
+/usr/include/bits/unistd.h:74:10: error: ‘__pread_alias’ writing 58 or more bytes into a region of size 10 overflows the destination [-Werror=stringop-overflow=]
+   74 |   return __glibc_fortify (pread, __nbytes, sizeof (char),
+      |          ^~~~~~~~~~~~~~~
+/usr/include/ar.h: In function ‘core_file_read_eagerly’:
+/usr/include/ar.h:41:10: note: destination object ‘ar_size’ of size 10
+   41 |     char ar_size[10];           /* File size, in ASCII decimal.  */
+      |          ^~~~~~~
+/usr/include/bits/unistd.h:50:16: note: in a call to function ‘__pread_alias’ declared with attribute ‘access (write_only, 2, 3)’
+   50 | extern ssize_t __REDIRECT (__pread_alias,
+      |                ^~~~~~~~~~
+cc1: all warnings being treated as errors
+
+The warning disappears when dropping either -fsanitize=undefined
+or when using -D_FORTIFY_SOURCE=2. It looks like a false positive.
+But I haven't figured out how/why it happens.
+
+The code is a little tricky to proof correct though. The ar_size
+field is a not-zero terminated string ASCII decimal, right-padded
+with spaces. Which is then converted with strtoll. Relying on the
+fact that the struct ar_hdr is zero initialized, so there will be
+a zero byte after the ar_size field.
+
+Rewrite the code to just use a zero byte terminated char array.
+Which is much easier to reason about. As a bonus the error disappears.
+
+Signed-off-by: Mark Wielaard <[email-masked]>
+---
+ libdwfl/ChangeLog   |  5 +++++
+ libdwfl/core-file.c | 26 ++++++++++++++++----------
+ 2 files changed, 21 insertions(+), 10 deletions(-)
+
+diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
+index 75c53948d..acdaa0138 100644
+--- a/libdwfl/ChangeLog
++++ b/libdwfl/ChangeLog
+@@ -1,0 +1,5 @@
++2022-07-28  Mark Wielaard  <[email-masked]>
++
++	* core-file.c (elf_begin_rand): Replace struct ar_hdr h with
++	a char ar_size[AR_SIZE_CHARS + 1] array to read size.
++
+2022-04-22  Mark Wielaard  <[email-masked]>
+
+	* debuginfod-client.c (init_control): New static pthread_once_t.
+diff --git a/libdwfl/core-file.c b/libdwfl/core-file.c
+index cefc3db0f..4418ef338 100644
+--- a/libdwfl/core-file.c
++++ b/libdwfl/core-file.c
+@@ -75,26 +75,32 @@ elf_begin_rand (Elf *parent, off_t offset, off_t size, off_t *next)
+      from the archive header to override SIZE.  */
+   if (parent->kind == ELF_K_AR)
+     {
+-      struct ar_hdr h = { .ar_size = "" };
+-
+-      if (unlikely (parent->maximum_size - offset < sizeof h))
++      /* File size, in ASCII decimal, right-padded with ASCII spaces.
++         Max 10 characters. Not zero terminated. So make this ar_size
++         array one larger and explicitly zero terminate it.  As needed
++         for strtoll.  */
++      #define AR_SIZE_CHARS 10
++      char ar_size[AR_SIZE_CHARS + 1];
++      ar_size[AR_SIZE_CHARS] = '\0';
++
++      if (unlikely (parent->maximum_size - offset < sizeof (struct ar_hdr)))
+ 	return fail (ELF_E_RANGE);
+ 
+       if (parent->map_address != NULL)
+-	memcpy (h.ar_size, parent->map_address + parent->start_offset + offset,
+-		sizeof h.ar_size);
++	memcpy (ar_size, parent->map_address + parent->start_offset + offset,
++		AR_SIZE_CHARS);
+       else if (unlikely (pread_retry (parent->fildes,
+-				      h.ar_size, sizeof (h.ar_size),
++				      ar_size, AR_SIZE_CHARS,
+ 				      parent->start_offset + offset
+ 				      + offsetof (struct ar_hdr, ar_size))
+-			 != sizeof (h.ar_size)))
++			 != AR_SIZE_CHARS))
+ 	return fail (ELF_E_READ_ERROR);
+ 
+-      offset += sizeof h;
++      offset += sizeof (struct ar_hdr);
+ 
+       char *endp;
+-      size = strtoll (h.ar_size, &endp, 10);
+-      if (unlikely (endp == h.ar_size)
++      size = strtoll (ar_size, &endp, 10);
++      if (unlikely (endp == ar_size)
+ 	  || unlikely ((off_t) parent->maximum_size - offset < size))
+ 	return fail (ELF_E_INVALID_ARCHIVE);
+     }
+-- 
+cgit 
+

base-commit: e00ca95e08bc1cc2cb39f3178485ef16defce0be
prerequisite-patch-id: a1adabf857d746a919597ce5a4f50a391115748f
prerequisite-patch-id: bec1beee57f8cddaf583960ffb67c9badd172de7
prerequisite-patch-id: dcf9a53f458adf55547ef075c83a881c238d476e
-- 
2.46.0