fs/ntfs3: Sequential field availability check in mi_enum_attr()

commit 090f612756a9720ec18b0b130e28be49839d7cb5 upstream.

The code is slightly reformatted to consistently check field availability
without duplication.

Fixes: 556bdf27c2dd ("ntfs3: Add bounds checking to mi_enum_attr()")
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c
index d9e72d288222f62ddf2c1d9cd5d504cd9935a699..b2b98631a00090c50892a51d31aac57c066bf731 100644 (file)
--- a/fs/ntfs3/record.c
+++ b/fs/ntfs3/record.c
@@ -231,6 +231,7 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
        }
 
        /* Can we use the first field (attr->type). */
+       /* NOTE: this code also checks attr->size availability. */
        if (off + 8 > used) {
                static_assert(ALIGN(sizeof(enum ATTR_TYPE), 8) == 8);
                return NULL;
@@ -251,10 +252,6 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
                return NULL;
 
        asize = le32_to_cpu(attr->size);
-       if (asize < SIZEOF_RESIDENT) {
-               /* Impossible 'cause we should not return such attribute. */
-               return NULL;
-       }
 
        /* Check overflow and boundary. */
        if (off + asize < off || off + asize > used)
@@ -285,6 +282,10 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
        if (attr->non_res != 1)
                return NULL;
 
+       /* Can we use memory including attr->nres.valid_size? */
+       if (asize < SIZEOF_NONRESIDENT)
+               return NULL;
+
        t16 = le16_to_cpu(attr->nres.run_off);
        if (t16 > asize)
                return NULL;
@@ -311,7 +312,8 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
 
        if (!attr->nres.svcn && is_attr_ext(attr)) {
                /* First segment of sparse/compressed attribute */
-               if (asize + 8 < SIZEOF_NONRESIDENT_EX)
+               /* Can we use memory including attr->nres.total_size? */
+               if (asize < SIZEOF_NONRESIDENT_EX)
                        return NULL;
 
                tot_size = le64_to_cpu(attr->nres.total_size);
@@ -321,9 +323,6 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
                if (tot_size > alloc_size)
                        return NULL;
        } else {
-               if (asize + 8 < SIZEOF_NONRESIDENT)
-                       return NULL;
-
                if (attr->nres.c_unit)
                        return NULL;
        }