When using `--fixed-value` with a key whose value is left empty (implied
as being "true"), 'git config' may crash when invoked like either of:
$ git config set --file=config --value=value --fixed-value \
section.key pattern
$ git config --file=config --fixed-value section.key value pattern
The original bugreport[1] bisects to 00bbdde141 (builtin/config:
introduce "set" subcommand, 2024-05-06), which is a red-herring, since
the original bugreport uses the new 'git config set' invocation.
The behavior likely bisects back to c90702a1f6 (config: plumb
--fixed-value into config API, 2020-11-25), which introduces the new
--fixed-value option in the first place.
Looking at the relevant frame from a failed process's coredump, the
crash appears in config.c::matches() like so:
(gdb) up
#1 0x000055b3e8b06022 in matches (key=0x55b3ea894360 "section.key", value=0x0,
store=0x7ffe99076eb0) at config.c:2884
2884 return !strcmp(store->fixed_value, value);
where we are trying to compare the `--fixed-value` argument to `value`,
which is NULL.
Avoid attempting to match `--fixed-value` for configuration keys with no
explicit value. A future patch could consider the empty value to mean
"true", "yes", "on", etc. when invoked with `--type=bool`, but let's
punt on that for now in the name of avoiding the segfault.
[1]: https://lore.kernel.org/git/CANrWfmTek1xErBLrnoyhHN+gWU+rw14y6SQ+abZyzGoaBjmiKA@xxxxxxxxxxxxxx/
Reported-by: Han Jiang <jhcarl0814@xxxxxxxxx>
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
config.c | 2 +-
t/t1300-config.sh | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/config.c b/config.c
index 6421894614..05f369ec0d 100644
--- a/config.c
+++ b/config.c
@@ -2914,7 +2914,7 @@ static int matches(const char *key, const char *value,
{
if (strcmp(key, store->key))
return 0; /* not ours */
- if (store->fixed_value)
+ if (store->fixed_value && value)
return !strcmp(store->fixed_value, value);
if (!store->value_pattern)
return 1; /* always matches */
diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index 9de2d95f06..f13277c8f3 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -2704,6 +2704,15 @@ test_expect_success '--get and --get-all with --fixed-value' '
test_must_fail git config --file=config --get-regexp --fixed-value fixed+ non-existent
'
+test_expect_success '--fixed-value with value-less configuration' '
+ test_when_finished rm -f config &&
+ cat >config <<-\EOF &&
+ [section]
+ key
+ EOF
+ git config --file=config --fixed-value section.key value pattern
+'
+
test_expect_success 'includeIf.hasconfig:remote.*.url' '
git init hasremoteurlTest &&
test_when_finished "rm -rf hasremoteurlTest" &&
--
2.46.0.dirty
