[PATCH] kbuild: modversions: Fix relative CRC byte order interpretion

Fredrik Noring
2019-03-23T18:56:12Z

Fix commit 56067812d5b0 ("kbuild: modversions: add infrastructure for
emitting relative CRCs") where CRCs are interpreted in host byte order
rather than proper kernel byte order.

For example, when loading BE modules compiled with a LE system, the
error "disagrees about version of symbol module_layout" is produced.
A message such as "Found checksum D7FA6856 vs module 5668FAD7" will be
given with debug enabled, which indicates an obvious endian problem.

The general solution is to use the macro TO_NATIVE, as is done in
similar cases throughout modpost.c. With this correction it has been
verified that BE modules compiled with a LE system load properly into
a BE kernel.

Signed-off-by: Fredrik Noring <noring@nocrew.org>
Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs")
Cc: stable@vger.kernel.org
---
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 0b0d1080b1c5..f277e116e0eb 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -639,7 +639,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
info->sechdrs[sym->st_shndx].sh_offset -
(info->hdr->e_type != ET_REL ?
info->sechdrs[sym->st_shndx].sh_addr : 0);
- crc = *crcp;
+ crc = TO_NATIVE(*crcp);
}
sym_update_crc(symname + strlen("__crc_"), mod, crc,
export);