From: Eric Biggers ebiggers@google.com
commit 594bc43b410316d70bb42aeff168837888d96810 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: aa75f4d3daae ("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 --- fs/ext4/fast_commit.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -745,6 +745,9 @@ static u8 *ext4_fc_reserve_space(struct *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 sup 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);