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Date:   Tue, 27 Jun 2023 14:49:52 +0100
From:   Lee Jones <lee@kernel.org>
To:     Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc:     ntfs3@lists.linux.dev, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 09/14] fs/ntfs3: Check fields while reading
Message-ID: <20230627134952.GA1811280@google.com>
References: <fc5957cc-a71b-cfa3-f291-cb63b23800d1@paragon-software.com>
 <0ec81044-062c-29e0-c081-dff9484f0368@paragon-software.com>
 <20230619094133.GA1500182@google.com>
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In-Reply-To: <20230619094133.GA1500182@google.com>
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Konstantin,

On Mon, 19 Jun 2023, Lee Jones wrote:
> On Fri, 28 Oct 2022, Konstantin Komarov wrote:
> 
> > Added new functions index_hdr_check and index_buf_check.
> > Now we check all stuff for correctness while reading from disk.
> > Also fixed bug with stale nfs data.
> > 
> > Reported-by: van fantasy <g1042620637@gmail.com>
> > Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
> > ---
> >  fs/ntfs3/index.c   |  84 ++++++++++++++++++++++++++++++----
> >  fs/ntfs3/inode.c   |  18 ++++----
> >  fs/ntfs3/ntfs_fs.h |   4 +-
> >  fs/ntfs3/run.c     |   7 ++-
> >  fs/ntfs3/xattr.c   | 109 +++++++++++++++++++++++++++++----------------
> >  5 files changed, 164 insertions(+), 58 deletions(-)
> 
> It's not clear to me what route this patch took into Mainline [0].  My
> guess it was authored by and then merged by the maintainer after no one
> raised any review comments.
> 
> It does appear that this particular patch was identified as the fix for
> a published CVE however [1], and with no Fixes: tag I'm concerned that
> the Stable AUTOSEL bot may miss this.  With that in mind, would you mind
> submitting to the relevant Stable branches please?  [2] contains all of
> the relevant information if you're not 100% certain of the process.
> 
> Thank you.
> 
> [0] 0e8235d28f3a0 fs/ntfs3: Check fields while reading
> [1] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-48502
> [2] Documentation/process/stable-kernel-rules.rst

Can you confirm receipt of this mail please?

Would you be kind enough to submit your patch to Stable please?

> > diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
> > index 35369ae5c438..51ab75954640 100644
> > --- a/fs/ntfs3/index.c
> > +++ b/fs/ntfs3/index.c
> > @@ -605,11 +605,58 @@ static const struct NTFS_DE *hdr_insert_head(struct INDEX_HDR *hdr,
> >  	return e;
> >  }
> > +/*
> > + * index_hdr_check
> > + *
> > + * return true if INDEX_HDR is valid
> > + */
> > +static bool index_hdr_check(const struct INDEX_HDR *hdr, u32 bytes)
> > +{
> > +	u32 end = le32_to_cpu(hdr->used);
> > +	u32 tot = le32_to_cpu(hdr->total);
> > +	u32 off = le32_to_cpu(hdr->de_off);
> > +
> > +	if (!IS_ALIGNED(off, 8) || tot > bytes || end > tot ||
> > +	    off + sizeof(struct NTFS_DE) > end) {
> > +		/* incorrect index buffer. */
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +
> > +/*
> > + * index_buf_check
> > + *
> > + * return true if INDEX_BUFFER seems is valid
> > + */
> > +static bool index_buf_check(const struct INDEX_BUFFER *ib, u32 bytes,
> > +			    const CLST *vbn)
> > +{
> > +	const struct NTFS_RECORD_HEADER *rhdr = &ib->rhdr;
> > +	u16 fo = le16_to_cpu(rhdr->fix_off);
> > +	u16 fn = le16_to_cpu(rhdr->fix_num);
> > +
> > +	if (bytes <= offsetof(struct INDEX_BUFFER, ihdr) ||
> > +	    rhdr->sign != NTFS_INDX_SIGNATURE ||
> > +	    fo < sizeof(struct INDEX_BUFFER)
> > +	    /* Check index buffer vbn. */
> > +	    || (vbn && *vbn != le64_to_cpu(ib->vbn)) || (fo % sizeof(short)) ||
> > +	    fo + fn * sizeof(short) >= bytes ||
> > +	    fn != ((bytes >> SECTOR_SHIFT) + 1)) {
> > +		/* incorrect index buffer. */
> > +		return false;
> > +	}
> > +
> > +	return index_hdr_check(&ib->ihdr,
> > +			       bytes - offsetof(struct INDEX_BUFFER, ihdr));
> > +}
> > +
> >  void fnd_clear(struct ntfs_fnd *fnd)
> >  {
> >  	int i;
> > -	for (i = 0; i < fnd->level; i++) {
> > +	for (i = fnd->level - 1; i >= 0; i--) {
> >  		struct indx_node *n = fnd->nodes[i];
> >  		if (!n)
> > @@ -819,9 +866,16 @@ int indx_init(struct ntfs_index *indx, struct ntfs_sb_info *sbi,
> >  	u32 t32;
> >  	const struct INDEX_ROOT *root = resident_data(attr);
> > +	t32 = le32_to_cpu(attr->res.data_size);
> > +	if (t32 <= offsetof(struct INDEX_ROOT, ihdr) ||
> > +	    !index_hdr_check(&root->ihdr,
> > +			     t32 - offsetof(struct INDEX_ROOT, ihdr))) {
> > +		goto out;
> > +	}
> > +
> >  	/* Check root fields. */
> >  	if (!root->index_block_clst)
> > -		return -EINVAL;
> > +		goto out;
> >  	indx->type = type;
> >  	indx->idx2vbn_bits = __ffs(root->index_block_clst);
> > @@ -833,19 +887,19 @@ int indx_init(struct ntfs_index *indx, struct ntfs_sb_info *sbi,
> >  	if (t32 < sbi->cluster_size) {
> >  		/* Index record is smaller than a cluster, use 512 blocks. */
> >  		if (t32 != root->index_block_clst * SECTOR_SIZE)
> > -			return -EINVAL;
> > +			goto out;
> >  		/* Check alignment to a cluster. */
> >  		if ((sbi->cluster_size >> SECTOR_SHIFT) &
> >  		    (root->index_block_clst - 1)) {
> > -			return -EINVAL;
> > +			goto out;
> >  		}
> >  		indx->vbn2vbo_bits = SECTOR_SHIFT;
> >  	} else {
> >  		/* Index record must be a multiple of cluster size. */
> >  		if (t32 != root->index_block_clst << sbi->cluster_bits)
> > -			return -EINVAL;
> > +			goto out;
> >  		indx->vbn2vbo_bits = sbi->cluster_bits;
> >  	}
> > @@ -853,7 +907,14 @@ int indx_init(struct ntfs_index *indx, struct ntfs_sb_info *sbi,
> >  	init_rwsem(&indx->run_lock);
> >  	indx->cmp = get_cmp_func(root);
> > -	return indx->cmp ? 0 : -EINVAL;
> > +	if (!indx->cmp)
> > +		goto out;
> > +
> > +	return 0;
> > +
> > +out:
> > +	ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);
> > +	return -EINVAL;
> >  }
> >  static struct indx_node *indx_new(struct ntfs_index *indx,
> > @@ -1011,6 +1072,13 @@ int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
> >  		goto out;
> >  ok:
> > +	if (!index_buf_check(ib, bytes, &vbn)) {
> > +		ntfs_inode_err(&ni->vfs_inode, "directory corrupted");
> > +		ntfs_set_state(ni->mi.sbi, NTFS_DIRTY_ERROR);
> > +		err = -EINVAL;
> > +		goto out;
> > +	}
> > +
> >  	if (err == -E_NTFS_FIXUP) {
> >  		ntfs_write_bh(ni->mi.sbi, &ib->rhdr, &in->nb, 0);
> >  		err = 0;
> > @@ -1601,9 +1669,9 @@ static int indx_insert_into_root(struct ntfs_index *indx, struct ntfs_inode *ni,
> >  	if (err) {
> >  		/* Restore root. */
> > -		if (mi_resize_attr(mi, attr, -ds_root))
> > +		if (mi_resize_attr(mi, attr, -ds_root)) {
> >  			memcpy(attr, a_root, asize);
> > -		else {
> > +		} else {
> >  			/* Bug? */
> >  			ntfs_set_state(sbi, NTFS_DIRTY_ERROR);
> >  		}
> > diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
> > index 78ec3e6bbf67..719cf6fbb5ed 100644
> > --- a/fs/ntfs3/inode.c
> > +++ b/fs/ntfs3/inode.c
> > @@ -81,7 +81,7 @@ static struct inode *ntfs_read_mft(struct inode *inode,
> >  			 le16_to_cpu(ref->seq), le16_to_cpu(rec->seq));
> >  		goto out;
> >  	} else if (!is_rec_inuse(rec)) {
> > -		err = -EINVAL;
> > +		err = -ESTALE;
> >  		ntfs_err(sb, "Inode r=%x is not in use!", (u32)ino);
> >  		goto out;
> >  	}
> > @@ -92,8 +92,10 @@ static struct inode *ntfs_read_mft(struct inode *inode,
> >  		goto out;
> >  	}
> > -	if (!is_rec_base(rec))
> > -		goto Ok;
> > +	if (!is_rec_base(rec)) {
> > +		err = -EINVAL;
> > +		goto out;
> > +	}
> >  	/* Record should contain $I30 root. */
> >  	is_dir = rec->flags & RECORD_FLAG_DIR;
> > @@ -465,7 +467,6 @@ static struct inode *ntfs_read_mft(struct inode *inode,
> >  		inode->i_flags |= S_NOSEC;
> >  	}
> > -Ok:
> >  	if (ino == MFT_REC_MFT && !sb->s_root)
> >  		sbi->mft.ni = NULL;
> > @@ -519,6 +520,9 @@ struct inode *ntfs_iget5(struct super_block *sb, const struct MFT_REF *ref,
> >  		_ntfs_bad_inode(inode);
> >  	}
> > +	if (IS_ERR(inode) && name)
> > +		ntfs_set_state(sb->s_fs_info, NTFS_DIRTY_ERROR);
> > +
> >  	return inode;
> >  }
> > @@ -1652,10 +1656,8 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
> >  		ntfs_remove_reparse(sbi, IO_REPARSE_TAG_SYMLINK, &new_de->ref);
> >  out5:
> > -	if (S_ISDIR(mode) || run_is_empty(&ni->file.run))
> > -		goto out4;
> > -
> > -	run_deallocate(sbi, &ni->file.run, false);
> > +	if (!S_ISDIR(mode))
> > +		run_deallocate(sbi, &ni->file.run, false);
> >  out4:
> >  	clear_rec_inuse(rec);
> > diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
> > index d73d1c837ba7..c9b8a6f1ba0b 100644
> > --- a/fs/ntfs3/ntfs_fs.h
> > +++ b/fs/ntfs3/ntfs_fs.h
> > @@ -795,12 +795,12 @@ int run_pack(const struct runs_tree *run, CLST svcn, CLST len, u8 *run_buf,
> >  	     u32 run_buf_size, CLST *packed_vcns);
> >  int run_unpack(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
> >  	       CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
> > -	       u32 run_buf_size);
> > +	       int run_buf_size);
> >  #ifdef NTFS3_CHECK_FREE_CLST
> >  int run_unpack_ex(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
> >  		  CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
> > -		  u32 run_buf_size);
> > +		  int run_buf_size);
> >  #else
> >  #define run_unpack_ex run_unpack
> >  #endif
> > diff --git a/fs/ntfs3/run.c b/fs/ntfs3/run.c
> > index aaaa0d3d35a2..12d8682f33b5 100644
> > --- a/fs/ntfs3/run.c
> > +++ b/fs/ntfs3/run.c
> > @@ -919,12 +919,15 @@ int run_pack(const struct runs_tree *run, CLST svcn, CLST len, u8 *run_buf,
> >   */
> >  int run_unpack(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
> >  	       CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
> > -	       u32 run_buf_size)
> > +	       int run_buf_size)
> >  {
> >  	u64 prev_lcn, vcn64, lcn, next_vcn;
> >  	const u8 *run_last, *run_0;
> >  	bool is_mft = ino == MFT_REC_MFT;
> > +	if (run_buf_size < 0)
> > +		return -EINVAL;
> > +
> >  	/* Check for empty. */
> >  	if (evcn + 1 == svcn)
> >  		return 0;
> > @@ -1046,7 +1049,7 @@ int run_unpack(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
> >   */
> >  int run_unpack_ex(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
> >  		  CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
> > -		  u32 run_buf_size)
> > +		  int run_buf_size)
> >  {
> >  	int ret, err;
> >  	CLST next_vcn, lcn, len;
> > diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> > index aeee5fb12092..385c50831a8d 100644
> > --- a/fs/ntfs3/xattr.c
> > +++ b/fs/ntfs3/xattr.c
> > @@ -42,28 +42,26 @@ static inline size_t packed_ea_size(const struct EA_FULL *ea)
> >   * Assume there is at least one xattr in the list.
> >   */
> >  static inline bool find_ea(const struct EA_FULL *ea_all, u32 bytes,
> > -			   const char *name, u8 name_len, u32 *off)
> > +			   const char *name, u8 name_len, u32 *off, u32 *ea_sz)
> >  {
> > -	*off = 0;
> > +	u32 ea_size;
> > -	if (!ea_all || !bytes)
> > +	*off = 0;
> > +	if (!ea_all)
> >  		return false;
> > -	for (;;) {
> > +	for (; *off < bytes; *off += ea_size) {
> >  		const struct EA_FULL *ea = Add2Ptr(ea_all, *off);
> > -		u32 next_off = *off + unpacked_ea_size(ea);
> > -
> > -		if (next_off > bytes)
> > -			return false;
> > -
> > +		ea_size = unpacked_ea_size(ea);
> >  		if (ea->name_len == name_len &&
> > -		    !memcmp(ea->name, name, name_len))
> > +		    !memcmp(ea->name, name, name_len)) {
> > +			if (ea_sz)
> > +				*ea_sz = ea_size;
> >  			return true;
> > -
> > -		*off = next_off;
> > -		if (next_off >= bytes)
> > -			return false;
> > +		}
> >  	}
> > +
> > +	return false;
> >  }
> >  /*
> > @@ -74,12 +72,12 @@ static inline bool find_ea(const struct EA_FULL *ea_all, u32 bytes,
> >  static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
> >  			size_t add_bytes, const struct EA_INFO **info)
> >  {
> > -	int err;
> > +	int err = -EINVAL;
> >  	struct ntfs_sb_info *sbi = ni->mi.sbi;
> >  	struct ATTR_LIST_ENTRY *le = NULL;
> >  	struct ATTRIB *attr_info, *attr_ea;
> >  	void *ea_p;
> > -	u32 size;
> > +	u32 size, off, ea_size;
> >  	static_assert(le32_to_cpu(ATTR_EA_INFO) < le32_to_cpu(ATTR_EA));
> > @@ -96,24 +94,31 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
> >  	*info = resident_data_ex(attr_info, sizeof(struct EA_INFO));
> >  	if (!*info)
> > -		return -EINVAL;
> > +		goto out;
> >  	/* Check Ea limit. */
> >  	size = le32_to_cpu((*info)->size);
> > -	if (size > sbi->ea_max_size)
> > -		return -EFBIG;
> > +	if (size > sbi->ea_max_size) {
> > +		err = -EFBIG;
> > +		goto out;
> > +	}
> > +
> > +	if (attr_size(attr_ea) > sbi->ea_max_size) {
> > +		err = -EFBIG;
> > +		goto out;
> > +	}
> > -	if (attr_size(attr_ea) > sbi->ea_max_size)
> > -		return -EFBIG;
> > +	if (!size) {
> > +		/* EA info persists, but xattr is empty. Looks like EA problem. */
> > +		goto out;
> > +	}
> >  	/* Allocate memory for packed Ea. */
> >  	ea_p = kmalloc(size_add(size, add_bytes), GFP_NOFS);
> >  	if (!ea_p)
> >  		return -ENOMEM;
> > -	if (!size) {
> > -		/* EA info persists, but xattr is empty. Looks like EA problem. */
> > -	} else if (attr_ea->non_res) {
> > +	if (attr_ea->non_res) {
> >  		struct runs_tree run;
> >  		run_init(&run);
> > @@ -124,24 +129,52 @@ static int ntfs_read_ea(struct ntfs_inode *ni, struct EA_FULL **ea,
> >  		run_close(&run);
> >  		if (err)
> > -			goto out;
> > +			goto out1;
> >  	} else {
> >  		void *p = resident_data_ex(attr_ea, size);
> > -		if (!p) {
> > -			err = -EINVAL;
> > -			goto out;
> > -		}
> > +		if (!p)
> > +			goto out1;
> >  		memcpy(ea_p, p, size);
> >  	}
> >  	memset(Add2Ptr(ea_p, size), 0, add_bytes);
> > +
> > +	/* Check all attributes for consistency. */
> > +	for (off = 0; off < size; off += ea_size) {
> > +		const struct EA_FULL *ef = Add2Ptr(ea_p, off);
> > +		u32 bytes = size - off;
> > +
> > +		/* Check if we can use field ea->size. */
> > +		if (bytes < sizeof(ef->size))
> > +			goto out1;
> > +
> > +		if (ef->size) {
> > +			ea_size = le32_to_cpu(ef->size);
> > +			if (ea_size > bytes)
> > +				goto out1;
> > +			continue;
> > +		}
> > +
> > +		/* Check if we can use fields ef->name_len and ef->elength. */
> > +		if (bytes < offsetof(struct EA_FULL, name))
> > +			goto out1;
> > +
> > +		ea_size = ALIGN(struct_size(ef, name,
> > +					    1 + ef->name_len +
> > +						    le16_to_cpu(ef->elength)),
> > +				4);
> > +		if (ea_size > bytes)
> > +			goto out1;
> > +	}
> > +
> >  	*ea = ea_p;
> >  	return 0;
> > -out:
> > +out1:
> >  	kfree(ea_p);
> > -	*ea = NULL;
> > +out:
> > +	ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);
> >  	return err;
> >  }
> > @@ -163,6 +196,7 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
> >  	const struct EA_FULL *ea;
> >  	u32 off, size;
> >  	int err;
> > +	int ea_size;
> >  	size_t ret;
> >  	err = ntfs_read_ea(ni, &ea_all, 0, &info);
> > @@ -175,8 +209,9 @@ static ssize_t ntfs_list_ea(struct ntfs_inode *ni, char *buffer,
> >  	size = le32_to_cpu(info->size);
> >  	/* Enumerate all xattrs. */
> > -	for (ret = 0, off = 0; off < size; off += unpacked_ea_size(ea)) {
> > +	for (ret = 0, off = 0; off < size; off += ea_size) {
> >  		ea = Add2Ptr(ea_all, off);
> > +		ea_size = unpacked_ea_size(ea);
> >  		if (buffer) {
> >  			if (ret + ea->name_len + 1 > bytes_per_buffer) {
> > @@ -227,7 +262,8 @@ static int ntfs_get_ea(struct inode *inode, const char *name, size_t name_len,
> >  		goto out;
> >  	/* Enumerate all xattrs. */
> > -	if (!find_ea(ea_all, le32_to_cpu(info->size), name, name_len, &off)) {
> > +	if (!find_ea(ea_all, le32_to_cpu(info->size), name, name_len, &off,
> > +		     NULL)) {
> >  		err = -ENODATA;
> >  		goto out;
> >  	}
> > @@ -269,7 +305,7 @@ static noinline int ntfs_set_ea(struct inode *inode, const char *name,
> >  	struct EA_FULL *new_ea;
> >  	struct EA_FULL *ea_all = NULL;
> >  	size_t add, new_pack;
> > -	u32 off, size;
> > +	u32 off, size, ea_sz;
> >  	__le16 size_pack;
> >  	struct ATTRIB *attr;
> >  	struct ATTR_LIST_ENTRY *le;
> > @@ -304,9 +340,8 @@ static noinline int ntfs_set_ea(struct inode *inode, const char *name,
> >  		size_pack = ea_info.size_pack;
> >  	}
> > -	if (info && find_ea(ea_all, size, name, name_len, &off)) {
> > +	if (info && find_ea(ea_all, size, name, name_len, &off, &ea_sz)) {
> >  		struct EA_FULL *ea;
> > -		size_t ea_sz;
> >  		if (flags & XATTR_CREATE) {
> >  			err = -EEXIST;
> > @@ -329,8 +364,6 @@ static noinline int ntfs_set_ea(struct inode *inode, const char *name,
> >  		if (ea->flags & FILE_NEED_EA)
> >  			le16_add_cpu(&ea_info.count, -1);
> > -		ea_sz = unpacked_ea_size(ea);
> > -
> >  		le16_add_cpu(&ea_info.size_pack, 0 - packed_ea_size(ea));
> >  		memmove(ea, Add2Ptr(ea, ea_sz), size - off - ea_sz);
> > -- 
> > 2.37.0
> > 
> > 
> 
> -- 
> Lee Jones [李琼斯]

-- 
Lee Jones [李琼斯]