[5/6] btrfs-progs: check/original: Fix uninitialized extent buffer contents
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Message ID 20200324105315.136569-6-wqu@suse.com
State New
Headers show
  • btrfs-progs: Fixes for valgrind errors during fsck-tests
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Commit Message

Qu Wenruo March 24, 2020, 10:53 a.m. UTC
Valgrind reports the following error for fsck/012:
  adding new tree backref on start 4206592 len 4096 parent 0 root 5
  ==100735== Syscall param pwrite64(buf) points to uninitialised byte(s)
  ==100735==    at 0x49F303A: pwrite (in /usr/lib/libpthread-2.31.so)
  ==100735==    by 0x1A5C85: write_extent_to_disk (extent_io.c:815)
  ==100735==    by 0x1B2507: write_and_map_eb (disk-io.c:512)
  ==100735==    by 0x1B26A7: write_tree_block (disk-io.c:545)
  ==100735==    by 0x1D4822: __commit_transaction (transaction.c:148)
  ==100735==    by 0x1D4AA2: btrfs_commit_transaction (transaction.c:213)
  ==100735==    by 0x16360D: fixup_extent_refs (main.c:7662)
  ==100735==    by 0x16449F: check_extent_refs (main.c:8033)
  ==100735==    by 0x166199: check_chunks_and_extents (main.c:8786)
  ==100735==    by 0x166441: do_check_chunks_and_extents (main.c:8842)
  ==100735==    by 0x169D13: cmd_check (main.c:10324)
  ==100735==    by 0x11CDC6: cmd_execute (commands.h:125)
  ==100735==  Address 0x4e8aeb0 is 128 bytes inside a block of size 4,224 alloc'd
  ==100735==    at 0x483BB65: calloc (vg_replace_malloc.c:762)
  ==100735==    by 0x1A54C5: __alloc_extent_buffer (extent_io.c:609)
  ==100735==    by 0x1A5AD1: alloc_extent_buffer (extent_io.c:752)
  ==100735==    by 0x1B1A0A: btrfs_find_create_tree_block (disk-io.c:222)
  ==100735==    by 0x1BD4A2: btrfs_alloc_free_block (extent-tree.c:2538)
  ==100735==    by 0x1A8CE3: __btrfs_cow_block (ctree.c:322)
  ==100735==    by 0x1A91C6: btrfs_cow_block (ctree.c:415)
  ==100735==    by 0x1AB16C: btrfs_search_slot (ctree.c:1185)
  ==100735==    by 0x160BBC: delete_extent_records (main.c:6652)
  ==100735==    by 0x16343F: fixup_extent_refs (main.c:7629)
  ==100735==    by 0x16449F: check_extent_refs (main.c:8033)
  ==100735==    by 0x166199: check_chunks_and_extents (main.c:8786)

For new extent buffer allocated, we don't initialize its content.

This is not a major concern, at all.
For the above report, the reported range is inside the unused part of
the extent buffer, thus won't cause anything.

Regular btrfs_cow_block() will cover all the used ranges of one extent

But still, since kernel initialize the extent buffer with 0, it won't
hurt to do extra initialized to make valgrind happy.

Signed-off-by: Qu Wenruo <wqu@suse.com>
 extent_io.c | 1 +
 1 file changed, 1 insertion(+)

diff mbox series

diff --git a/extent_io.c b/extent_io.c
index f11917a4c6fc..4b5acb1aabf0 100644
--- a/extent_io.c
+++ b/extent_io.c
@@ -622,6 +622,7 @@  static struct extent_buffer *__alloc_extent_buffer(struct btrfs_fs_info *info,
 	eb->tree = &info->extent_cache;
+	memset_extent_buffer(eb, 0, 0, blocksize);
 	return eb;