[PATCH] jbd2: Fix memory leak in journal_init_common()

[Li Zetao]

There is a memory leak reported by kmemleak:

  unreferenced object 0xff11000105903b80 (size 64):
    comm "mount", pid 3382, jiffies 4295032021 (age 27.826s)
    hex dump (first 32 bytes):
      04 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
      ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00  ................
    backtrace:
      [<ffffffffae86ac40>] __kmalloc_node+0x50/0x160
      [<ffffffffaf2486d8>] crypto_alloc_tfmmem.isra.0+0x38/0x110
      [<ffffffffaf2498e5>] crypto_create_tfm_node+0x85/0x2f0
      [<ffffffffaf24a92c>] crypto_alloc_tfm_node+0xfc/0x210
      [<ffffffffaedde777>] journal_init_common+0x727/0x1ad0
      [<ffffffffaede1715>] jbd2_journal_init_inode+0x2b5/0x500
      [<ffffffffaed786b5>] ext4_load_and_init_journal+0x255/0x2440
      [<ffffffffaed8b423>] ext4_fill_super+0x8823/0xa330
      ...

The root cause was traced to an error handing path in journal_init_common()
when malloc memory failed in register_shrinker(). The checksum driver is
used to reference to checksum algorithm via cryptoapi and the user should
release the memory when the driver is no longer needed or the journal
initialization failed.

Fix it by calling crypto_free_shash() on the "err_cleanup" error handing
path in journal_init_common().

Fixes: c30713084ba5 ("jbd2: move load_superblock() into journal_init_common()")
Signed-off-by: Li Zetao <lizetao1@xxxxxxxxxx>
---
 fs/jbd2/journal.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 768fa05bcbed..30dec2bd2ecc 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1601,6 +1601,8 @@ static journal_t *journal_init_common(struct block_device *bdev,
 
 err_cleanup:
 	percpu_counter_destroy(&journal->j_checkpoint_jh_count);
+	if (journal->j_chksum_driver)
+		crypto_free_shash(journal->j_chksum_driver);
 	kfree(journal->j_wbuf);
 	jbd2_journal_destroy_revoke(journal);
 	journal_fail_superblock(journal);
-- 
2.34.1