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Commit df070afd authored by Ronnie Sahlberg's avatar Ronnie Sahlberg Committed by Steve French
Browse files

cifs: fix parsing of symbolic link error response 



RHBZ: 1672539

In smb2_query_symlink(), if we are parsing the error buffer but it is not something
we recognize as a symlink we should return -EINVAL and not -ENOENT.
I.e. the entry does exist, it is just not something we recognize.

Additionally, add check to verify that that the errortag and the reparsetag all make sense.

Signed-off-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Acked-by: default avatarPaulo Alcantara <palcantara@suse.de>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent f5f111c2

fs/cifs/smb2ops.c

+10 −4
Original line number Diff line number Diff line
@@ -2605,26 +2605,32 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon, 
	err_buf = err_iov.iov_base;

	if (le32_to_cpu(err_buf->ByteCount) < sizeof(struct smb2_symlink_err_rsp) ||

	    err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE) {

		rc = -ENOENT;

		rc = -EINVAL;

		goto querty_exit;

	}



	symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;

	if (le32_to_cpu(symlink->SymLinkErrorTag) != SYMLINK_ERROR_TAG ||

	    le32_to_cpu(symlink->ReparseTag) != IO_REPARSE_TAG_SYMLINK) {

		rc = -EINVAL;

		goto querty_exit;

	}



	/* open must fail on symlink - reset rc */

	rc = 0;

	symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;

	sub_len = le16_to_cpu(symlink->SubstituteNameLength);

	sub_offset = le16_to_cpu(symlink->SubstituteNameOffset);

	print_len = le16_to_cpu(symlink->PrintNameLength);

	print_offset = le16_to_cpu(symlink->PrintNameOffset);



	if (err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE + sub_offset + sub_len) {

		rc = -ENOENT;

		rc = -EINVAL;

		goto querty_exit;

	}



	if (err_iov.iov_len <

	    SMB2_SYMLINK_STRUCT_SIZE + print_offset + print_len) {

		rc = -ENOENT;

		rc = -EINVAL;

		goto querty_exit;

	}

fs/cifs/smb2pdu.h

+2 −0
Original line number Diff line number Diff line
@@ -166,6 +166,8 @@ struct smb2_err_rsp { 
	__u8   ErrorData[1];  /* variable length */

} __packed;



#define SYMLINK_ERROR_TAG 0x4c4d5953



struct smb2_symlink_err_rsp {

	__le32 SymLinkLength;

	__le32 SymLinkErrorTag;