From: Eric Biggers ebiggers@google.com

Validate the inode and filename lengths in fast-commit journal records so that a malicious fast-commit journal cannot cause a crash by having invalid values for these. Also validate EXT4_FC_TAG_DEL_RANGE.

Fixes: aa75f4d3daae ("ext4: main fast-commit commit path") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Eric Biggers ebiggers@google.com --- fs/ext4/fast_commit.c | 38 +++++++++++++++++++------------------- fs/ext4/fast_commit.h | 2 +- 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index 1e8be05542396..d5ad4b2b235d6 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -1991,32 +1991,31 @@ void ext4_fc_replay_cleanup(struct super_block *sb) kfree(sbi->s_fc_replay_state.fc_modified_inodes); }

-static inline bool ext4_fc_tag_len_isvalid(struct ext4_fc_tl *tl, - u8 *val, u8 *end) +static bool ext4_fc_value_len_isvalid(struct ext4_sb_info *sbi, + int tag, int len) { - if (val + tl->fc_len > end) - return false; - - /* Here only check ADD_RANGE/TAIL/HEAD which will read data when do - * journal rescan before do CRC check. Other tags length check will - * rely on CRC check. - */ - switch (tl->fc_tag) { + switch (tag) { case EXT4_FC_TAG_ADD_RANGE: - return (sizeof(struct ext4_fc_add_range) == tl->fc_len); - case EXT4_FC_TAG_TAIL: - return (sizeof(struct ext4_fc_tail) <= tl->fc_len); - case EXT4_FC_TAG_HEAD: - return (sizeof(struct ext4_fc_head) == tl->fc_len); + return len == sizeof(struct ext4_fc_add_range); case EXT4_FC_TAG_DEL_RANGE: + return len == sizeof(struct ext4_fc_del_range); + case EXT4_FC_TAG_CREAT: case EXT4_FC_TAG_LINK: case EXT4_FC_TAG_UNLINK: - case EXT4_FC_TAG_CREAT: + len -= sizeof(struct ext4_fc_dentry_info); + return len >= 1 && len <= EXT4_NAME_LEN; case EXT4_FC_TAG_INODE: + len -= sizeof(struct ext4_fc_inode); + return len >= EXT4_GOOD_OLD_INODE_SIZE && + len <= sbi->s_inode_size; case EXT4_FC_TAG_PAD: - default: - return true; + return true; /* padding can have any length */ + case EXT4_FC_TAG_TAIL: + return len >= sizeof(struct ext4_fc_tail); + case EXT4_FC_TAG_HEAD: + return len == sizeof(struct ext4_fc_head); } + return false; }

/* @@ -2079,7 +2078,8 @@ static int ext4_fc_replay_scan(journal_t *journal, cur = cur + EXT4_FC_TAG_BASE_LEN + tl.fc_len) { ext4_fc_get_tl(&tl, cur); val = cur + EXT4_FC_TAG_BASE_LEN; - if (!ext4_fc_tag_len_isvalid(&tl, val, end)) { + if (tl.fc_len > end - val || + !ext4_fc_value_len_isvalid(sbi, tl.fc_tag, tl.fc_len)) { ret = state->fc_replay_num_tags ? JBD2_FC_REPLAY_STOP : -ECANCELED; goto out_err; diff --git a/fs/ext4/fast_commit.h b/fs/ext4/fast_commit.h index 256f2ad27204a..2fadb2c4780c8 100644 --- a/fs/ext4/fast_commit.h +++ b/fs/ext4/fast_commit.h @@ -58,7 +58,7 @@ struct ext4_fc_dentry_info { __u8 fc_dname[]; };

-/* Value structure for EXT4_FC_TAG_INODE and EXT4_FC_TAG_INODE_PARTIAL. */ +/* Value structure for EXT4_FC_TAG_INODE. */ struct ext4_fc_inode { __le32 fc_ino; __u8 fc_raw_inode[];