The patch titled
Subject: objtool: do not retrieve data from empty sections
has been added to the -mm tree. Its filename is
objtool-do-not-retrieve-data-from-empty-sections.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/objtool-do-not-retrieve-data-from-empty-sections.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/objtool-do-not-retrieve-data-from-empty-sections.patch
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------------------------------------------------------
From: Petr Vandrovec <petr@xxxxxxxxxxxxxx>
Subject: objtool: do not retrieve data from empty sections
Binutils 2.29-9 in Debian returns an error when elf_getdata is invoked on
empty section (.note.GNU-stack in all kernel files), causing immediate
failure of kernel build with:
elf_getdata: can't manipulate null section
As nothing is done with sections that have zero size, just do not retrieve
their data at all.
Link: http://lkml.kernel.org/r/20170914191111.embq3bfkppem3l5u@xxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Petr Vandrovec <petr@xxxxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/objtool/elf.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff -puN tools/objtool/elf.c~objtool-do-not-retrieve-data-from-empty-sections tools/objtool/elf.c
--- a/tools/objtool/elf.c~objtool-do-not-retrieve-data-from-empty-sections
+++ a/tools/objtool/elf.c
@@ -175,19 +175,20 @@ static int read_sections(struct elf *elf
return -1;
}
- sec->data = elf_getdata(s, NULL);
- if (!sec->data) {
- WARN_ELF("elf_getdata");
- return -1;
+ if (sec->sh.sh_size != 0) {
+ sec->data = elf_getdata(s, NULL);
+ if (!sec->data) {
+ WARN_ELF("elf_getdata");
+ return -1;
+ }
+ if (sec->data->d_off != 0 ||
+ sec->data->d_size != sec->sh.sh_size) {
+ WARN("unexpected data attributes for %s",
+ sec->name);
+ return -1;
+ }
}
-
- if (sec->data->d_off != 0 ||
- sec->data->d_size != sec->sh.sh_size) {
- WARN("unexpected data attributes for %s", sec->name);
- return -1;
- }
-
- sec->len = sec->data->d_size;
+ sec->len = sec->sh.sh_size;
}
/* sanity check, one more call to elf_nextscn() should return NULL */
_
Patches currently in -mm which might be from petr@xxxxxxxxxxxxxx are
objtool-do-not-retrieve-data-from-empty-sections.patch
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