@matheusbsbs / matheus-bagliano / commits / 615d2de3b4

config.c: avoid segfault with --fixed-value and valueless config

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@mail.gmail.com/ Reported-by: Han Jiang <jhcarl0814@gmail.com> Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Taylor Blau committed Aug 1, 2024 at 13:06 UTC 615d2de3b457272216d4179ceb82b3b2b86b1929

2 files changed +10 -1

config.c

+1 -1

@@ -2876,7 +2876,7 @@ static int matches(const char *key, const char *value,

2876 {

2877 if (strcmp(key, store->key))

2878 return 0; /* not ours */

2879 - if (store->fixed_value)

2879 + if (store->fixed_value && value)

2880 return !strcmp(store->fixed_value, value);

2881 if (!store->value_pattern)

2882 return 1; /* always matches */

t/t1300-config.sh

@@ -2434,6 +2434,15 @@ test_expect_success '--get and --get-all with --fixed-value' '

2434 test_must_fail git config --file=config --get-regexp --fixed-value fixed+ non-existent

2435 '

2436

2437 +test_expect_success '--fixed-value with value-less configuration' '

2438 + test_when_finished rm -f config &&

2439 + cat >config <<-\EOF &&

2440 + [section]

2441 + key

2442 + EOF

2443 + git config --file=config --fixed-value section.key value pattern

2444 +'

2445 +

2446 test_expect_success 'includeIf.hasconfig:remote.*.url' '

2447 git init hasremoteurlTest &&

2448 test_when_finished "rm -rf hasremoteurlTest" &&