Commit df968c93 authored Sep 15, 2017 by Petr Vandrovec Committed by Ingo Molnar Sep 15, 2017

objtool: Do not retrieve data from empty sections



Binutils 2.29-9 in Debian return 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.

Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2ce30a44349065b70d0f00e71e286dc0cbe745e6.1505459652.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 0998b7a0

tools/objtool/elf.c

+13 −12

Original line number	Diff line number	Diff line
		@@ -175,19 +175,20 @@ static int read_sections(struct elf *elf)
		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);
		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 */