kconfig: Clear "written" flag to avoid data loss

commit 0c5b6c28ed68becb692b43eae5e44d5aa7e160ce upstream.

Prior to this commit, starting nconfig, xconfig or gconfig, and saving
the .config file more than once caused data loss, where a .config file
that contained only comments would be written to disk starting from the
second save operation.

This bug manifests itself because the SYMBOL_WRITTEN flag is never
cleared after the first call to conf_write, and subsequent calls to
conf_write then skip all of the configuration symbols due to the
SYMBOL_WRITTEN flag being set.

This commit resolves this issue by clearing the SYMBOL_WRITTEN flag
from all symbols before conf_write returns.

Fixes: 8e2442a5f86e ("kconfig: fix missing choice values in auto.conf")
Cc: linux-stable <stable@vger.kernel.org> # 4.19+
Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index a245255cecb266771b4bdd2d8ac279adf9453b8b..27964917cbfd82c08cd36a7424defbd04295e544 100644 (file)
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -867,6 +867,7 @@ int conf_write(const char *name)
        const char *str;
        char tmpname[PATH_MAX + 1], oldname[PATH_MAX + 1];
        char *env;
+       int i;
        bool need_newline = false;
 
        if (!name)
@@ -949,6 +950,9 @@ next:
        }
        fclose(out);
 
+       for_all_symbols(i, sym)
+               sym->flags &= ~SYMBOL_WRITTEN;
+
        if (*tmpname) {
                if (is_same(name, tmpname)) {
                        conf_message("No change to %s", name);