gnu: elfutils: Fix cross-compilation.

* gnu/packages/elf.scm (elfutils): Fix cross-compilation
[arguments]: When cross-compilation, apply patch.
<#:phases>: Use G-expressions.
* gnu/packages/patches/elfutils-libdwfl-string-overflow.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.

Change-Id: Ia1ab9c09124a140608bda34bf62f0ae80eb44f9b

1 files changed, 116 insertions, 0 deletions

diff --git a/gnu/packages/patches/elfutils-libdwfl-string-overflow.patch b/gnu/packages/patches/elfutils-libdwfl-string-overflow.patch
new file mode 100644
index 0000000000..e9d51359c4
--- /dev/null
+++ b/gnu/packages/patches/elfutils-libdwfl-string-overflow.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 <mark@klomp.org>
+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 <mark@klomp.org>
+---
+ 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  <mark@klomp.org>
++
++	* 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  <mark@klomp.org>
+
+	* 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 
+