modpost: do not try to match the SHT_NUL section.

Trying to match the SHT_NUL section isn't useful and causes build failures
on parisc and mn10300 since the addition of section strict white-listing
and __ex_table sanitizing.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 050e57fd5936 ("modpost: add strict white-listing when referencing....")
Fixes: 52dc0595d540 ("modpost: handle relocations mismatch in __ex_table.")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 9 insertions, 0 deletions

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index fd949770da0c..45e4027d3193 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1064,6 +1064,15 @@ static const struct sectioncheck *section_mismatch(
         int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck);
         const struct sectioncheck *check = &sectioncheck[0];
 
+        /*
+         * The target section could be the SHT_NUL section when we're
+         * handling relocations to un-resolved symbols, trying to match it
+         * doesn't make much sense and causes build failures on parisc and
+         * mn10300 architectures.
+         */
+        if (*tosec == '\0')
+                return NULL;
+
         for (i = 0; i < elems; i++) {
                 if (match(fromsec, check->fromsec)) {
                         if (check->bad_tosec[0] && match(tosec, check->bad_tosec))