As demonstrated in the previous commit, `git log --invert-grep` without
a `--grep` argument causes a segfault after f41fb662f5 (revisions API:
have release_revisions() release "grep_filter", 2022-04-13).
The segfault occurs in `free_pattern_expr()`, which crashes on trying to
switch on `x->node` when given a NULL pointer. Usually we avoid calling
`free_pattern_expr()` without a pattern as indicated by the `extended`
bit being zero.
But it is possible to get into a state where the `extended` bit is
non-zero, but the `pattern_expression` is still NULL. This happens
because the `--invert-grep` option sets the `no_body_match` bit. When we
call `compile_grep_patterns()`, we set `opt->extended = 1`. But the
`pattern_expression` is left as NULL, since we return with a NULL
`header_expr`.
So when we try to call `free_pattern_expr()`, things go awry, since
`free_grep_patterns()` expects a non-NULL argument.
Instead, teach `free_grep_patterns()` to tolerate a NULL argument
(treating it as a noop), and avoid checking whether or not the
`extended` bit is set, since `free_pattern_expr()` will handle its
argument regardless.
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
grep.c | 5 +++--
t/t4202-log.sh | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/grep.c b/grep.c
index 52a894c989..bcc6e63365 100644
--- a/grep.c
+++ b/grep.c
@@ -752,6 +752,9 @@ void compile_grep_patterns(struct grep_opt *opt)
static void free_pattern_expr(struct grep_expr *x)
{
+ if (!x)
+ return;
+
switch (x->node) {
case GREP_NODE_TRUE:
case GREP_NODE_ATOM:
@@ -790,8 +793,6 @@ void free_grep_patterns(struct grep_opt *opt)
free(p);
}
- if (!opt->extended)
- return;
free_pattern_expr(opt->pattern_expression);
}
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index e3ec5f5661..44f7ef0ea2 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -297,7 +297,7 @@ test_expect_success 'log --invert-grep --grep -i' '
fi
'
-test_expect_failure 'log --invert-grep (no --grep)' '
+test_expect_success 'log --invert-grep (no --grep)' '
git log --pretty="tformat:%s" >expect &&
git log --invert-grep --pretty="tformat:%s" >actual &&
test_cmp expect actual
--
2.37.0.1.g1379af2e9d
