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Subject[PATCH v2] kconfig: avoid an infinite loop in oldconfig/syncconfig
Date
Exit on error when asking for value that has an invalid default value
and stdin has reached EOF. This happens in particular for hex/int
configs without an explicit default value.

Previously, this case would loop:
* oldconfig prompts for the value but stdin has reached EOF
* It gets the global default value : an empty string
* This is not a valid hex/int value so it prompts again, hence the infinite loop.

This case happens with a configuration like this (a hex config without a
valid default value):
config TEST_KCONFIG
hex "Test KConfig"
# default 0x0

And using:
make oldconfig < /dev/null

This was discovered when working on Yocto bug[0] on a downstream
kconfig user (U-boot)

[0]: https://bugzilla.yoctoproject.org/show_bug.cgi?id=14136

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
v1->v2:
* Improve coding style
* Put more info in the commit message

scripts/kconfig/conf.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index 7cf63261d951c..8f32cbbce4805 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -377,8 +377,16 @@ static int conf_string(struct menu *menu)
line[strlen(line)-1] = 0;
def = line;
}
- if (def && sym_set_string_value(sym, def))
+ if (def && sym_set_string_value(sym, def)) {
return 0;
+ } else {
+ if (feof(stdin) && !sym_string_valid(sym, sym_get_string_value(sym))) {
+ fprintf(stderr,
+ "Symbol %s has invalid default value and stdin reached EOF\n",
+ sym->name);
+ exit(1);
+ }
+ }
}
}

--
2.30.2
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