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pack-bitmap: remove checks before bitmap_free

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In pack-bitmap.c:find_boundary_objects(), the roots_bitmap is only freed
if cascade_pseudo_merges_1() fails. However, cascade_pseudo_merges_1()
uses roots_bitmap as a mutable reference without taking ownership of it.
As a result, if cascade_pseudo_merges_1() succeeds, roots_bitmap is leaked.
And this leak currently lacks a dedicated test to detect it.

To fix this leak, remove if cascade_pseudo_merges_1() succeed check and
always calling bitmap_free(roots_bitmap);

To trigger this leak, we need roots_bitmap that contains at least one
pseudo merge. So that we can use pseudo merge bitmap when we compute roots
reachable bitmap. Here we create two commits: first A then B. Add A
to the pseudo-merge and perform a traversal over the range A..B.
In this scenario, the "haves" set will be {A}, and cascade_pseudo_merges_1
will succeed, thereby exposing the leak due to the missing roots_bitmap
cleanup.

Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Lidong Yan
2025-06-09 08:18:44 +00:00
committed by Junio C Hamano
parent fcfe60668e
commit 81cd1eef7d
2 changed files with 19 additions and 2 deletions
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4
pack-bitmap.c
View File

@@ -1363,8 +1363,8 @@ static struct bitmap *find_boundary_objects(struct bitmap_index *bitmap_git,
bitmap_set(roots_bitmap, pos); bitmap_set(roots_bitmap, pos);
} }
if (!cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap)) cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap);
bitmap_free(roots_bitmap); bitmap_free(roots_bitmap);
} }
/* /*

17
t/t5333-pseudo-merge-bitmaps.sh
View File

@@ -445,4 +445,21 @@ test_expect_success 'pseudo-merge closure' '
) )
' '
test_expect_success 'use pseudo-merge in boundary traversal' '
git init pseudo-merge-boundary-traversal &&
(
cd pseudo-merge-boundary-traversal &&
git config bitmapPseudoMerge.test.pattern refs/ &&
git config pack.useBitmapBoundaryTraversal true &&
test_commit A &&
git repack -adb &&
test_commit B &&
nr=$(git rev-list --count --use-bitmap-index HEAD~1..HEAD) &&
test 1 -eq "$nr"
)
'
test_done test_done