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. The bug is conditional on CONFIG_MODULE_REL_CRCS. For example, when loading a BE module into a BE kernel 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 within __kcrctab within the kernel image. 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 a BE kernel compiled with a LE system accepts BE modules. This change has also been verified with a LE kernel compiled with a LE system, in which case TO_NATIVE returns its value unmodified since the byte orders match. This is by far the common case. Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs") Signed-off-by: Fredrik Noring <noring@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- Thank you for your review, Masahiro, Changes in v2: - Fix subject spelling mistake. - Note that the bug is conditional on CONFIG_MODULE_REL_CRCS. - Clarify kernel image and __kcrctab compilation details. - Mention verification of matching LE byte order common case. Fredrik --- 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);