Commit 943deb60 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by Steve French
Browse files

cifs: Replace a couple of one-element arrays with flexible-array members 

One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element arrays with flexible-array
member in structs negotiate_req and extended_response, and refactor the
rest of the code, accordingly.

Also, make use of the DECLARE_FLEX_ARRAY() helper to declare flexible
array member EncryptionKey in union u. This new helper allows for
flexible-array members in unions.

Change pointer notation to proper array notation in a call to memcpy()
where flexible-array member DialectsArray is being used as destination
argument.

Important to mention is that doing a build before/after this patch results
in no binary output differences.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/229
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836

 [1]
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 4659f01e

fs/cifs/cifspdu.h

+4 −3
Original line number Diff line number Diff line
@@ -483,7 +483,7 @@ put_bcc(__u16 count, struct smb_hdr *hdr) 
typedef struct negotiate_req {

	struct smb_hdr hdr;	/* wct = 0 */

	__le16 ByteCount;

	unsigned char DialectsArray[1];

	unsigned char DialectsArray[];

} __attribute__((packed)) NEGOTIATE_REQ;



#define MIN_TZ_ADJ (15 * 60) /* minimum grid for timezones in seconds */
@@ -508,13 +508,14 @@ typedef struct negotiate_rsp { 
	__u8 EncryptionKeyLength;

	__u16 ByteCount;

	union {

		unsigned char EncryptionKey[1];	/* cap extended security off */

		/* cap extended security off */

		DECLARE_FLEX_ARRAY(unsigned char, EncryptionKey);

		/* followed by Domain name - if extended security is off */

		/* followed by 16 bytes of server GUID */

		/* then security blob if cap_extended_security negotiated */

		struct {

			unsigned char GUID[SMB1_CLIENT_GUID_SIZE];

			unsigned char SecurityBlob[1];

			unsigned char SecurityBlob[];

		} __attribute__((packed)) extended_response;

	} __attribute__((packed)) u;

} __attribute__((packed)) NEGOTIATE_RSP;

fs/cifs/cifssmb.c

+1 −1
Original line number Diff line number Diff line
@@ -465,7 +465,7 @@ CIFSSMBNegotiate(const unsigned int xid, 
	for (i = 0; i < CIFS_NUM_PROT; i++) {

		size_t len = strlen(protocols[i].name) + 1;



		memcpy(pSMB->DialectsArray+count, protocols[i].name, len);

		memcpy(&pSMB->DialectsArray[count], protocols[i].name, len);

		count += len;

	}

	inc_rfc1001_len(pSMB, count);