From: Eric Biggers <ebiggers@kernel.org> stable inclusion from stable-v5.10.269 commit add98959b220935b243170214c787bc03044a44d category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18652 CVE: CVE-2026-80806 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit da32af420d6d466e247c43ac0b829edeac7ae0ad upstream. Currently, when a new encrypted regular file is created, the call to ext4_set_inode_flags(inode, init=true) in __ext4_new_inode() is made before EXT4_INODE_ENCRYPT is set. As a result, it can set S_DAX if the filesystem is mounted with "-o dax=always". EXT4_INODE_ENCRYPT then actually gets set a bit later in __ext4_new_inode(), when it calls fscrypt_set_context() which calls ext4_set_context(). ext4_set_context() sets EXT4_INODE_ENCRYPT and calls ext4_set_inode_flags(inode, init=false) to set S_ENCRYPTED too. This was intended to clear S_DAX as well. However, this was broken by commit 043546e46dc7 ("fs/ext4: Only change S_DAX on inode load"). This causes data written to the file to bypass encryption, also causing xfstests failures such as generic/548 (when "-o dax=always" is used). Fix this by simplifying the flow by making __ext4_new_inode() set EXT4_INODE_ENCRYPT earlier. This makes it take effect in ext4_set_inode_flags(inode, init=true), making S_DAX never be set. Similarly, make EXT4_STATE_MAY_INLINE_DATA never be set in the first place on new encrypted inodes. Then it doesn't need to be cleared. As a result of these simplifications, ext4_set_context() no longer needs to change inode flags or state when 'handle != NULL'. Remove that too. Reported-by: Disha Goel <disgoel@linux.ibm.com> Reported-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Closes: https://lore.kernel.org/r/20260723085648.1500357-1-ojaswin@linux.ibm.com Fixes: 043546e46dc7 ("fs/ext4: Only change S_DAX on inode load") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org> Tested-by: Disha Goel <disgoel@linux.ibm.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260730175212.36923-1-ebiggers@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Erkun <yangerkun@huawei.com> --- fs/ext4/ialloc.c | 4 ++++ fs/ext4/super.c | 40 ++++++++++++++++++++-------------------- 2 files changed, 24 insertions(+), 20 deletions(-) diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index b0d0ca8f4389..97077402253f 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -986,6 +986,8 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir, err = fscrypt_prepare_new_inode(dir, inode, &encrypt); if (err) goto out; + if (encrypt) + i_flags |= EXT4_ENCRYPT_FL; } err = dquot_initialize(inode); @@ -1298,6 +1300,8 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir, ei->i_extra_isize = sbi->s_want_extra_isize; ei->i_inline_off = 0; if (ext4_has_feature_inline_data(sb) && + /* Encrypted inodes cannot have inline data */ + !(ei->i_flags & EXT4_ENCRYPT_FL) && (!(ei->i_flags & EXT4_DAX_FL) || S_ISDIR(mode))) ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); ret = inode; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 35df5a3f84e3..c4bf643a0fd0 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1565,7 +1565,13 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len, if (inode->i_ino == EXT4_ROOT_INO) return -EPERM; - if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode))) + /* + * For new encrypted inodes, S_DAX is never set in the first place. + * + * For existing inodes, this is called only on empty directories. ext4 + * never sets S_DAX on directories. + */ + if (WARN_ON_ONCE(IS_DAX(inode))) return -EINVAL; if (ext4_test_inode_flag(inode, EXT4_INODE_DAX)) @@ -1584,21 +1590,18 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len, */ if (handle) { - res = ext4_xattr_set_handle(handle, inode, - EXT4_XATTR_INDEX_ENCRYPTION, - EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, - ctx, len, 0); - if (!res) { - ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT); - ext4_clear_inode_state(inode, - EXT4_STATE_MAY_INLINE_DATA); - /* - * Update inode->i_flags - S_ENCRYPTED will be enabled, - * S_DAX may be disabled - */ - ext4_set_inode_flags(inode, false); - } - return res; + /* + * __ext4_new_inode() should have already set the encrypt flag + * on the inode and avoided enabling inline data. + */ + if (WARN_ON_ONCE(!IS_ENCRYPTED(inode))) + return -EINVAL; + if (WARN_ON_ONCE(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))) + return -EINVAL; + return ext4_xattr_set_handle(handle, inode, + EXT4_XATTR_INDEX_ENCRYPTION, + EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, + ctx, len, 0); } res = dquot_initialize(inode); @@ -1619,10 +1622,7 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len, ctx, len, 0); if (!res) { ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT); - /* - * Update inode->i_flags - S_ENCRYPTED will be enabled, - * S_DAX may be disabled - */ + /* Update inode->i_flags to set S_ENCRYPTED. */ ext4_set_inode_flags(inode, false); res = ext4_mark_inode_dirty(handle, inode); if (res) -- 2.52.0