[v2] bundle-uri: plug leak in unbundle_from_file()

Commit Message

Toon Claes Oct. 10, 2024, 9:12 a.m. UTC

The function `unbundle_from_file()` has two memory leaks:

  - We do not release the `struct bundle_header header` when hitting
    errors because we return early without any cleanup.

  - We do not release the `struct strbuf bundle_ref` at all.

Plug these leaks by creating a common exit path where both of these
variables are released.

While at it, refactor the code such that the variable assignments do not
happen inside the conditional statement itself according to our coding
style.

Signed-off-by: Toon Claes <[e-mail]>
---
 bundle-uri.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)


Range-diff against v1:
1:  f30f393e05 ! 1:  19714d860c bundle-uri: plug leak in unbundle_from_file()
    @@ Metadata
      ## Commit message ##
         bundle-uri: plug leak in unbundle_from_file()
     
    -    When the function returns early, the variable bundle_ref is not released
    -    through strbuf_release().
    +    The function `unbundle_from_file()` has two memory leaks:
     
    -    Fix this leak. And while at it, remove assignments in the conditions of
    -    the "if" statements as suggested in the CodingGuidelines.
    +      - We do not release the `struct bundle_header header` when hitting
    +        errors because we return early without any cleanup.
    +
    +      - We do not release the `struct strbuf bundle_ref` at all.
    +
    +    Plug these leaks by creating a common exit path where both of these
    +    variables are released.
    +
    +    While at it, refactor the code such that the variable assignments do not
    +    happen inside the conditional statement itself according to our coding
    +    style.
     
         Signed-off-by: Toon Claes <[e-mail]>
     
    @@ bundle-uri.c: static int unbundle_from_file(struct repository *r, const char *fi
     -		return 1;
     +	result = unbundle(r, &header, bundle_fd, NULL,
     +			  VERIFY_BUNDLE_QUIET | (fetch_pack_fsck_objects() ? VERIFY_BUNDLE_FSCK : 0));
    -+	if (result)
    ++	if (result) {
    ++		result = 1;
     +		goto cleanup;
    ++	}
      
      	/*
      	 * Convert all refs/heads/ from the bundle into refs/bundles/

Comments

Patrick Steinhardt Oct. 10, 2024, 12:55 p.m. UTC | #1

On Thu, Oct 10, 2024 at 11:12:49AM +0200, Toon Claes wrote:
> The function `unbundle_from_file()` has two memory leaks:
> 
>   - We do not release the `struct bundle_header header` when hitting
>     errors because we return early without any cleanup.
> 
>   - We do not release the `struct strbuf bundle_ref` at all.
> 
> Plug these leaks by creating a common exit path where both of these
> variables are released.
> 
> While at it, refactor the code such that the variable assignments do not
> happen inside the conditional statement itself according to our coding
> style.

Thanks, this version looks good to me. We now avoid any discussion
around the changed error code completely, and the commit message seems
reasonable to me.

Thanks!

Patrick

Junio C Hamano Oct. 10, 2024, 6:47 p.m. UTC | #2

Patrick Steinhardt <[e-mail]> writes:

> On Thu, Oct 10, 2024 at 11:12:49AM +0200, Toon Claes wrote:
>> The function `unbundle_from_file()` has two memory leaks:
>> 
>>   - We do not release the `struct bundle_header header` when hitting
>>     errors because we return early without any cleanup.
>> 
>>   - We do not release the `struct strbuf bundle_ref` at all.
>> 
>> Plug these leaks by creating a common exit path where both of these
>> variables are released.
>> 
>> While at it, refactor the code such that the variable assignments do not
>> happen inside the conditional statement itself according to our coding
>> style.
>
> Thanks, this version looks good to me. We now avoid any discussion
> around the changed error code completely, and the commit message seems
> reasonable to me.
>
> Thanks!
>
> Patrick

Thanks, both of you.

Will queue.

Patch

diff --git a/bundle-uri.c b/bundle-uri.c
index 4b1a2e2937..0df66e2872 100644
--- a/bundle-uri.c
+++ b/bundle-uri.c
@@ -368,17 +368,23 @@  static int unbundle_from_file(struct repository *r, const char *file)
 	struct strbuf bundle_ref = STRBUF_INIT;
 	size_t bundle_prefix_len;
 
-	if ((bundle_fd = read_bundle_header(file, &header)) < 0)
-		return 1;
+	bundle_fd = read_bundle_header(file, &header);
+	if (bundle_fd < 0) {
+		result = 1;
+		goto cleanup;
+	}
 
 	/*
 	 * Skip the reachability walk here, since we will be adding
 	 * a reachable ref pointing to the new tips, which will reach
 	 * the prerequisite commits.
 	 */
-	if ((result = unbundle(r, &header, bundle_fd, NULL,
-			       VERIFY_BUNDLE_QUIET | (fetch_pack_fsck_objects() ? VERIFY_BUNDLE_FSCK : 0))))
-		return 1;
+	result = unbundle(r, &header, bundle_fd, NULL,
+			  VERIFY_BUNDLE_QUIET | (fetch_pack_fsck_objects() ? VERIFY_BUNDLE_FSCK : 0));
+	if (result) {
+		result = 1;
+		goto cleanup;
+	}
 
 	/*
 	 * Convert all refs/heads/ from the bundle into refs/bundles/
@@ -407,6 +413,8 @@  static int unbundle_from_file(struct repository *r, const char *file)
 				0, UPDATE_REFS_MSG_ON_ERR);
 	}
 
+cleanup:
+	strbuf_release(&bundle_ref);
 	bundle_header_release(&header);
 	return result;
 }