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Since cascade_pseudo_merges_1() only use roots_bitmap as a mutable reference but not takes roots_bitmap's ownership. Once cascade_pseudo_merges_1 succeed(), roots_bitmap leaks. 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 a pseudo-merge whose size is equal to or smaller than roots_bitmap (which corresponds to the set of "haves" commits in prepare_bitmap_walk()). To do this, we can create two commits: A and B. Add A to the pseudo-merge list 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> --- pack-bitmap: remove checks before bitmap_free In pack-bitmap.c:find_boundary_objects, remove cascade success check and always free roots_bitmap afterward to make static analysis tool works better. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1977%2Fbrandb97%2Fremove-check-before-bitmap-free-v3 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1977/brandb97/remove-check-before-bitmap-free-v3 Pull-Request: https://github.com/git/git/pull/1977 Range-diff vs v2: 1: d7b7a0e29ec < -: ----------- pack-bitmap: remove checks before bitmap_free 2: 56b24d681cb ! 1: 151a7f5dc70 t5333: test memory leak when use pseudo-merge in boundary traversal @@ Metadata Author: Lidong Yan <502024330056@smail.nju.edu.cn> ## Commit message ## - t5333: test memory leak when use pseudo-merge in boundary traversal + pack-bitmap: remove checks before bitmap_free In pack-bitmap.c:find_boundary_objects(), the roots_bitmap is only freed - if cascade_pseudo_merges_1() fails. Otherwise, it leaks, leading to - a memory leak that currently lacks a dedicated test to detect it. + if cascade_pseudo_merges_1() fails. Since cascade_pseudo_merges_1() only + use roots_bitmap as a mutable reference but not takes roots_bitmap's + ownership. Once cascade_pseudo_merges_1 succeed(), roots_bitmap leaks. + 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 a pseudo-merge whose size is equal to or smaller than roots_bitmap (which corresponds to the set of "haves" commits in prepare_bitmap_walk()). To do this, we can create two commits: A and B. Add A to the pseudo-merge list 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 + 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> + ## pack-bitmap.c ## +@@ pack-bitmap.c: static struct bitmap *find_boundary_objects(struct bitmap_index *bitmap_git, + bitmap_set(roots_bitmap, pos); + } + +- if (!cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap)) +- bitmap_free(roots_bitmap); ++ cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap); ++ bitmap_free(roots_bitmap); + } + + /* + ## t/t5333-pseudo-merge-bitmaps.sh ## @@ t/t5333-pseudo-merge-bitmaps.sh: test_expect_success 'pseudo-merge closure' ' ) @@ t/t5333-pseudo-merge-bitmaps.sh: test_expect_success 'pseudo-merge closure' ' + git config bitmapPseudoMerge.test.pattern refs/ && + git config bitmapPseudoMerge.test.threshold now && + git config bitmapPseudoMerge.test.stableThreshold now && -+ export GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1 && ++ GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1 && + + test_commit A && + git repack -adb && pack-bitmap.c | 4 ++-- t/t5333-pseudo-merge-bitmaps.sh | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+), 2 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index ac6d62b980c..8727f316de9 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -1363,8 +1363,8 @@ static struct bitmap *find_boundary_objects(struct bitmap_index *bitmap_git, bitmap_set(roots_bitmap, pos); } - if (!cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap)) - bitmap_free(roots_bitmap); + cascade_pseudo_merges_1(bitmap_git, cb.base, roots_bitmap); + bitmap_free(roots_bitmap); } /* diff --git a/t/t5333-pseudo-merge-bitmaps.sh b/t/t5333-pseudo-merge-bitmaps.sh index 56674db562f..454f8c7a817 100755 --- a/t/t5333-pseudo-merge-bitmaps.sh +++ b/t/t5333-pseudo-merge-bitmaps.sh @@ -445,4 +445,24 @@ 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 bitmapPseudoMerge.test.threshold now && + git config bitmapPseudoMerge.test.stableThreshold now && + GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1 && + + test_commit A && + git repack -adb && + test_commit B && + + echo '1' >expect && + git rev-list --count --use-bitmap-index HEAD~1..HEAD >actual && + test_cmp expect actual + ) +' + test_done base-commit: 845c48a16a7f7b2c44d8cb137b16a4a1f0140229 -- gitgitgadget