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

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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: Kees Cook <keescook@chromium.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Gustavo A. R. Silva 2022-10-04 20:51:39 -05:00 committed by Steve French
parent 4659f01e3c
commit 943deb6066
2 changed files with 5 additions and 4 deletions
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7
fs/cifs/cifspdu.h
View File

@ -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;

2
fs/cifs/cifssmb.c
View File

@ -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);