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ext4: fix leaking uninitialized memory in fast-commit journal 

commit 594bc43b41 upstream.

When space at the end of fast-commit journal blocks is unused, make sure
to zero it out so that uninitialized memory is not leaked to disk.

Fixes: aa75f4d3da ("ext4: main fast-commit commit path")
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221106224841.279231-4-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Biggers 2022-11-06 14:48:37 -08:00 committed by Greg Kroah-Hartman
parent 0bdcac7469
commit d9ba03eb03
1 changed files with 5 additions and 0 deletions
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5
fs/ext4/fast_commit.c
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@ -745,6 +745,9 @@ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc)
*crc = ext4_chksum(sbi, *crc, tl, EXT4_FC_TAG_BASE_LEN);
if (pad_len > 0)
ext4_fc_memzero(sb, tl + 1, pad_len, crc);
/* Don't leak uninitialized memory in the unused last byte. */
*((u8 *)(tl + 1) + pad_len) = 0;
ext4_fc_submit_bh(sb, false);
ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh);
@ -801,6 +804,8 @@ static int ext4_fc_write_tail(struct super_block *sb, u32 crc)
dst += sizeof(tail.fc_tid);
tail.fc_crc = cpu_to_le32(crc);
ext4_fc_memcpy(sb, dst, &tail.fc_crc, sizeof(tail.fc_crc), NULL);
dst += sizeof(tail.fc_crc);
memset(dst, 0, bsize - off); /* Don't leak uninitialized memory. */
ext4_fc_submit_bh(sb, true);