[PATCH] cifs: Replace remaining 1-element arrays

From: Kees Cook
Date: Tue Feb 14 2023 - 19:09:54 EST

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The kernel is globally removing the ambiguous 0-length and 1-element
arrays in favor of flexible arrays, so that we can gain both compile-time
and run-time array bounds checking[1].

Replace the trailing 1-element array with a flexible array in the
following structures:

struct cifs_spnego_msg
struct cifs_quota_data
struct get_dfs_referral_rsp
struct file_alt_name_info
NEGOTIATE_RSP
SESSION_SETUP_ANDX
TCONX_REQ
TCONX_RSP
TCONX_RSP_EXT
ECHO_REQ
ECHO_RSP
OPEN_REQ
OPENX_REQ
LOCK_REQ
RENAME_REQ
COPY_REQ
COPY_RSP
NT_RENAME_REQ
DELETE_FILE_REQ
DELETE_DIRECTORY_REQ
CREATE_DIRECTORY_REQ
QUERY_INFORMATION_REQ
SETATTR_REQ
TRANSACT_IOCTL_REQ
TRANSACT_CHANGE_NOTIFY_REQ
TRANSACTION2_QPI_REQ
TRANSACTION2_SPI_REQ
TRANSACTION2_FFIRST_REQ
TRANSACTION2_GET_DFS_REFER_REQ
FILE_UNIX_LINK_INFO
FILE_DIRECTORY_INFO
FILE_FULL_DIRECTORY_INFO
SEARCH_ID_FULL_DIR_INFO
FILE_BOTH_DIRECTORY_INFO
FIND_FILE_STANDARD_INFO

Replace the trailing 1-element array with a flexible array, but leave
the existing structure padding:

FILE_ALL_INFO
FILE_UNIX_INFO

Remove unused structures:

struct gea
struct gealist

Adjust all related size calculations to match the changes to sizeof().

No machine code output differences are produced after these changes.

[1] For lots of details, see both:
https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays
https://people.kernel.org/kees/bounded-flexible-arrays-in-c

Cc: Steve French <sfrench@xxxxxxxxx>
Cc: Paulo Alcantara <pc@xxxxxx>
Cc: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Cc: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Cc: linux-cifs@xxxxxxxxxxxxxxx
Cc: samba-technical@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/cifs/cifs_spnego.h | 2 +-
fs/cifs/cifspdu.h | 94 +++++++++++++++++++++----------------------
fs/cifs/readdir.c | 6 +--
fs/cifs/smb2pdu.c | 4 +-
fs/cifs/smb2pdu.h | 2 +-
5 files changed, 52 insertions(+), 56 deletions(-)

diff --git a/fs/cifs/cifs_spnego.h b/fs/cifs/cifs_spnego.h
index 7f102ffeb675..e4d751b0c812 100644
--- a/fs/cifs/cifs_spnego.h
+++ b/fs/cifs/cifs_spnego.h
@@ -24,7 +24,7 @@ struct cifs_spnego_msg {
uint32_t flags;
uint32_t sesskey_len;
uint32_t secblob_len;
- uint8_t data[1];
+ uint8_t data[];
};

#ifdef __KERNEL__
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index add73be4902c..445e3eaebcc1 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -562,7 +562,7 @@ typedef union smb_com_session_setup_andx {
__u32 Reserved;
__le32 Capabilities; /* see below */
__le16 ByteCount;
- unsigned char SecurityBlob[1]; /* followed by */
+ unsigned char SecurityBlob[]; /* followed by */
/* STRING NativeOS */
/* STRING NativeLanMan */
} __attribute__((packed)) req; /* NTLM request format (with
@@ -582,7 +582,7 @@ typedef union smb_com_session_setup_andx {
__u32 Reserved; /* see below */
__le32 Capabilities;
__le16 ByteCount;
- unsigned char CaseInsensitivePassword[1]; /* followed by: */
+ unsigned char CaseInsensitivePassword[]; /* followed by: */
/* unsigned char * CaseSensitivePassword; */
/* STRING AccountName */
/* STRING PrimaryDomain */
@@ -599,7 +599,7 @@ typedef union smb_com_session_setup_andx {
__le16 Action; /* see below */
__le16 SecurityBlobLength;
__u16 ByteCount;
- unsigned char SecurityBlob[1]; /* followed by */
+ unsigned char SecurityBlob[]; /* followed by */
/* unsigned char * NativeOS; */
/* unsigned char * NativeLanMan; */
/* unsigned char * PrimaryDomain; */
@@ -618,7 +618,7 @@ typedef union smb_com_session_setup_andx {
__le16 PasswordLength;
__u32 Reserved; /* encrypt key len and offset */
__le16 ByteCount;
- unsigned char AccountPassword[1]; /* followed by */
+ unsigned char AccountPassword[]; /* followed by */
/* STRING AccountName */
/* STRING PrimaryDomain */
/* STRING NativeOS */
@@ -632,7 +632,7 @@ typedef union smb_com_session_setup_andx {
__le16 AndXOffset;
__le16 Action; /* see below */
__u16 ByteCount;
- unsigned char NativeOS[1]; /* followed by */
+ unsigned char NativeOS[]; /* followed by */
/* unsigned char * NativeLanMan; */
/* unsigned char * PrimaryDomain; */
} __attribute__((packed)) old_resp; /* pre-NTLM (LANMAN2.1) response */
@@ -693,7 +693,7 @@ typedef struct smb_com_tconx_req {
__le16 Flags; /* see below */
__le16 PasswordLength;
__le16 ByteCount;
- unsigned char Password[1]; /* followed by */
+ unsigned char Password[]; /* followed by */
/* STRING Path *//* \\server\share name */
/* STRING Service */
} __attribute__((packed)) TCONX_REQ;
@@ -705,7 +705,7 @@ typedef struct smb_com_tconx_rsp {
__le16 AndXOffset;
__le16 OptionalSupport; /* see below */
__u16 ByteCount;
- unsigned char Service[1]; /* always ASCII, not Unicode */
+ unsigned char Service[]; /* always ASCII, not Unicode */
/* STRING NativeFileSystem */
} __attribute__((packed)) TCONX_RSP;

@@ -718,7 +718,7 @@ typedef struct smb_com_tconx_rsp_ext {
__le32 MaximalShareAccessRights;
__le32 GuestMaximalShareAccessRights;
__u16 ByteCount;
- unsigned char Service[1]; /* always ASCII, not Unicode */
+ unsigned char Service[]; /* always ASCII, not Unicode */
/* STRING NativeFileSystem */
} __attribute__((packed)) TCONX_RSP_EXT;

@@ -755,14 +755,14 @@ typedef struct smb_com_echo_req {
struct smb_hdr hdr;
__le16 EchoCount;
__le16 ByteCount;
- char Data[1];
+ char Data[];
} __attribute__((packed)) ECHO_REQ;

typedef struct smb_com_echo_rsp {
struct smb_hdr hdr;
__le16 SequenceNumber;
__le16 ByteCount;
- char Data[1];
+ char Data[];
} __attribute__((packed)) ECHO_RSP;

typedef struct smb_com_logoff_andx_req {
@@ -862,7 +862,7 @@ typedef struct smb_com_open_req { /* also handles create */
__le32 ImpersonationLevel;
__u8 SecurityFlags;
__le16 ByteCount;
- char fileName[1];
+ char fileName[];
} __attribute__((packed)) OPEN_REQ;

/* open response: oplock levels */
@@ -937,7 +937,7 @@ typedef struct smb_com_openx_req {
__le32 Timeout;
__le32 Reserved;
__le16 ByteCount; /* file name follows */
- char fileName[1];
+ char fileName[];
} __attribute__((packed)) OPENX_REQ;

typedef struct smb_com_openx_rsp {
@@ -1085,7 +1085,7 @@ typedef struct smb_com_lock_req {
__le16 NumberOfUnlocks;
__le16 NumberOfLocks;
__le16 ByteCount;
- LOCKING_ANDX_RANGE Locks[1];
+ LOCKING_ANDX_RANGE Locks[];
} __attribute__((packed)) LOCK_REQ;

/* lock type */
@@ -1114,7 +1114,7 @@ typedef struct smb_com_rename_req {
__le16 SearchAttributes; /* target file attributes */
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII or Unicode */
- unsigned char OldFileName[1];
+ unsigned char OldFileName[];
/* followed by __u8 BufferFormat2 */
/* followed by NewFileName */
} __attribute__((packed)) RENAME_REQ;
@@ -1134,7 +1134,7 @@ typedef struct smb_com_copy_req {
__le16 Flags;
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII or Unicode */
- unsigned char OldFileName[1];
+ unsigned char OldFileName[];
/* followed by __u8 BufferFormat2 */
/* followed by NewFileName string */
} __attribute__((packed)) COPY_REQ;
@@ -1144,7 +1144,7 @@ typedef struct smb_com_copy_rsp {
__le16 CopyCount; /* number of files copied */
__u16 ByteCount; /* may be zero */
__u8 BufferFormat; /* 0x04 - only present if errored file follows */
- unsigned char ErrorFileName[1]; /* only present if error in copy */
+ unsigned char ErrorFileName[]; /* only present if error in copy */
} __attribute__((packed)) COPY_RSP;

#define CREATE_HARD_LINK 0x103
@@ -1158,7 +1158,7 @@ typedef struct smb_com_nt_rename_req { /* A5 - also used for create hardlink */
__le32 ClusterCount;
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII or Unicode */
- unsigned char OldFileName[1];
+ unsigned char OldFileName[];
/* followed by __u8 BufferFormat2 */
/* followed by NewFileName */
} __attribute__((packed)) NT_RENAME_REQ;
@@ -1173,7 +1173,7 @@ typedef struct smb_com_delete_file_req {
__le16 SearchAttributes;
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII */
- unsigned char fileName[1];
+ unsigned char fileName[];
} __attribute__((packed)) DELETE_FILE_REQ;

typedef struct smb_com_delete_file_rsp {
@@ -1185,7 +1185,7 @@ typedef struct smb_com_delete_directory_req {
struct smb_hdr hdr; /* wct = 0 */
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII */
- unsigned char DirName[1];
+ unsigned char DirName[];
} __attribute__((packed)) DELETE_DIRECTORY_REQ;

typedef struct smb_com_delete_directory_rsp {
@@ -1197,7 +1197,7 @@ typedef struct smb_com_create_directory_req {
struct smb_hdr hdr; /* wct = 0 */
__le16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII */
- unsigned char DirName[1];
+ unsigned char DirName[];
} __attribute__((packed)) CREATE_DIRECTORY_REQ;

typedef struct smb_com_create_directory_rsp {
@@ -1209,7 +1209,7 @@ typedef struct smb_com_query_information_req {
struct smb_hdr hdr; /* wct = 0 */
__le16 ByteCount; /* 1 + namelen + 1 */
__u8 BufferFormat; /* 4 = ASCII */
- unsigned char FileName[1];
+ unsigned char FileName[];
} __attribute__((packed)) QUERY_INFORMATION_REQ;

typedef struct smb_com_query_information_rsp {
@@ -1229,7 +1229,7 @@ typedef struct smb_com_setattr_req {
__le16 reserved[5]; /* must be zero */
__u16 ByteCount;
__u8 BufferFormat; /* 4 = ASCII */
- unsigned char fileName[1];
+ unsigned char fileName[];
} __attribute__((packed)) SETATTR_REQ;

typedef struct smb_com_setattr_rsp {
@@ -1311,7 +1311,7 @@ typedef struct smb_com_transaction_ioctl_req {
__u8 IsRootFlag; /* 1 = apply command to root of share (must be DFS) */
__le16 ByteCount;
__u8 Pad[3];
- __u8 Data[1];
+ __u8 Data[];
} __attribute__((packed)) TRANSACT_IOCTL_REQ;

typedef struct smb_com_transaction_compr_ioctl_req {
@@ -1430,7 +1430,7 @@ typedef struct smb_com_transaction_change_notify_req {
__u8 Reserved2;
__le16 ByteCount;
/* __u8 Pad[3];*/
-/* __u8 Data[1];*/
+/* __u8 Data[];*/
} __attribute__((packed)) TRANSACT_CHANGE_NOTIFY_REQ;

/* BB eventually change to use generic ntransact rsp struct
@@ -1519,7 +1519,7 @@ struct cifs_quota_data {
__u64 space_used;
__u64 soft_limit;
__u64 hard_limit;
- char sid[1]; /* variable size? */
+ char sid[]; /* variable size? */
} __attribute__((packed));

/* quota sub commands */
@@ -1671,7 +1671,7 @@ typedef struct smb_com_transaction2_qpi_req {
__u8 Pad;
__le16 InformationLevel;
__u32 Reserved4;
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) TRANSACTION2_QPI_REQ;

typedef struct smb_com_transaction2_qpi_rsp {
@@ -1704,7 +1704,7 @@ typedef struct smb_com_transaction2_spi_req {
__u16 Pad1;
__le16 InformationLevel;
__u32 Reserved4;
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) TRANSACTION2_SPI_REQ;

typedef struct smb_com_transaction2_spi_rsp {
@@ -1809,7 +1809,7 @@ typedef struct smb_com_transaction2_ffirst_req {
__le16 SearchFlags;
__le16 InformationLevel;
__le32 SearchStorageType;
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) TRANSACTION2_FFIRST_REQ;

typedef struct smb_com_transaction2_ffirst_rsp {
@@ -2020,7 +2020,7 @@ typedef struct smb_com_transaction2_get_dfs_refer_req {
perhaps?) followed by one byte pad - doesn't
seem to matter though */
__le16 MaxReferralLevel;
- char RequestFileName[1];
+ char RequestFileName[];
} __attribute__((packed)) TRANSACTION2_GET_DFS_REFER_REQ;

#define DFS_VERSION cpu_to_le16(0x0003)
@@ -2049,7 +2049,7 @@ struct get_dfs_referral_rsp {
__le16 PathConsumed;
__le16 NumberOfReferrals;
__le32 DFSFlags;
- REFERRAL3 referrals[1]; /* array of level 3 dfs_referral structures */
+ REFERRAL3 referrals[]; /* array of level 3 dfs_referral structures */
/* followed by the strings pointed to by the referral structures */
} __packed;

@@ -2284,7 +2284,10 @@ typedef struct { /* data block encoding of response to level 263 QPathInfo */
__le32 Mode;
__le32 AlignmentRequirement;
__le32 FileNameLength;
- char FileName[1];
+ union {
+ char __pad;
+ DECLARE_FLEX_ARRAY(char, FileName);
+ };
} __attribute__((packed)) FILE_ALL_INFO; /* level 0x107 QPathInfo */

typedef struct {
@@ -2322,7 +2325,7 @@ typedef struct {
} __attribute__((packed)) FILE_UNIX_BASIC_INFO; /* level 0x200 QPathInfo */

typedef struct {
- char LinkDest[1];
+ DECLARE_FLEX_ARRAY(char, LinkDest);
} __attribute__((packed)) FILE_UNIX_LINK_INFO; /* level 0x201 QPathInfo */

/* The following three structures are needed only for
@@ -2371,7 +2374,7 @@ struct file_end_of_file_info {
} __attribute__((packed)); /* size info, level 0x104 for set, 0x106 for query */

struct file_alt_name_info {
- __u8 alt_name[1];
+ DECLARE_FLEX_ARRAY(__u8, alt_name);
} __attribute__((packed)); /* level 0x0108 */

struct file_stream_info {
@@ -2480,7 +2483,10 @@ typedef struct {
__le32 NextEntryOffset;
__u32 ResumeKey; /* as with FileIndex - no need to convert */
FILE_UNIX_BASIC_INFO basic;
- char FileName[1];
+ union {
+ char __pad;
+ DECLARE_FLEX_ARRAY(char, FileName);
+ };
} __attribute__((packed)) FILE_UNIX_INFO; /* level 0x202 */

typedef struct {
@@ -2494,7 +2500,7 @@ typedef struct {
__le64 AllocationSize;
__le32 ExtFileAttributes;
__le32 FileNameLength;
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) FILE_DIRECTORY_INFO; /* level 0x101 FF resp data */

typedef struct {
@@ -2509,7 +2515,7 @@ typedef struct {
__le32 ExtFileAttributes;
__le32 FileNameLength;
__le32 EaSize; /* length of the xattrs */
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) FILE_FULL_DIRECTORY_INFO; /* level 0x102 rsp data */

typedef struct {
@@ -2526,7 +2532,7 @@ typedef struct {
__le32 EaSize; /* EA size */
__le32 Reserved;
__le64 UniqueId; /* inode num - le since Samba puts ino in low 32 bit*/
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) SEARCH_ID_FULL_DIR_INFO; /* level 0x105 FF rsp data */

typedef struct {
@@ -2544,7 +2550,7 @@ typedef struct {
__u8 ShortNameLength;
__u8 Reserved;
__u8 ShortName[24];
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) FILE_BOTH_DIRECTORY_INFO; /* level 0x104 FFrsp data */

typedef struct {
@@ -2559,7 +2565,7 @@ typedef struct {
__le32 AllocationSize;
__le16 Attributes; /* verify not u32 */
__u8 FileNameLength;
- char FileName[1];
+ char FileName[];
} __attribute__((packed)) FIND_FILE_STANDARD_INFO; /* level 0x1 FF resp data */

@@ -2569,16 +2575,6 @@ struct win_dev {
__le64 minor;
} __attribute__((packed));

-struct gea {
- unsigned char name_len;
- char name[1];
-} __attribute__((packed));
-
-struct gealist {
- unsigned long list_len;
- struct gea list[1];
-} __attribute__((packed));
-
struct fea {
unsigned char EA_flags;
__u8 name_len;
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 2d75ba5aaa8a..ef638086d734 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -495,7 +495,7 @@ static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)
FIND_FILE_STANDARD_INFO *pfData;
pfData = (FIND_FILE_STANDARD_INFO *)pDirInfo;

- new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) +
+ new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) + 1 +
pfData->FileNameLength;
} else {
u32 next_offset = le32_to_cpu(pDirInfo->NextEntryOffset);
@@ -513,9 +513,9 @@ static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)
new_entry, end_of_smb, old_entry);
return NULL;
} else if (((level == SMB_FIND_FILE_INFO_STANDARD) &&
- (new_entry + sizeof(FIND_FILE_STANDARD_INFO) > end_of_smb))
+ (new_entry + sizeof(FIND_FILE_STANDARD_INFO) + 1 > end_of_smb))
|| ((level != SMB_FIND_FILE_INFO_STANDARD) &&
- (new_entry + sizeof(FILE_DIRECTORY_INFO) > end_of_smb))) {
+ (new_entry + sizeof(FILE_DIRECTORY_INFO) + 1 > end_of_smb))) {
cifs_dbg(VFS, "search entry %p extends after end of SMB %p\n",
new_entry, end_of_smb);
return NULL;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index c304678514a5..4982f5e65e13 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -5010,10 +5010,10 @@ smb2_parse_query_directory(struct cifs_tcon *tcon,

switch (srch_inf->info_level) {
case SMB_FIND_FILE_DIRECTORY_INFO:
- info_buf_size = sizeof(FILE_DIRECTORY_INFO) - 1;
+ info_buf_size = sizeof(FILE_DIRECTORY_INFO);
break;
case SMB_FIND_FILE_ID_FULL_DIR_INFO:
- info_buf_size = sizeof(SEARCH_ID_FULL_DIR_INFO) - 1;
+ info_buf_size = sizeof(SEARCH_ID_FULL_DIR_INFO);
break;
case SMB_FIND_FILE_POSIX_INFO:
/* note that posix payload are variable size */
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index a5773a06aba8..2114e8a0c63a 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -371,7 +371,7 @@ struct smb2_file_id_extd_directory_info {
__le32 EaSize; /* EA size */
__le32 ReparsePointTag; /* valid if FILE_ATTR_REPARSE_POINT set in FileAttributes */
__le64 UniqueId; /* inode num - le since Samba puts ino in low 32 bit */
- char FileName[1];
+ char FileName[];
} __packed; /* level 60 */

extern char smb2_padding[7];
--
2.34.1

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