mei: revamp mei extension header structure layout.

The mei extension header was build as array of flexible structures
which will not work if actually more headers are added.
(Currently only vtag header was used).
Sparse reports:

drivers/misc/mei/hw.h:253:32: warning: array of flexible structures

Use basic type u8 for the variable sized extension.
Define explicitly mei_ext_hdr_vtag structure.
And also fix mei_ext_next() function to point correctly to the
end of the header.

Note: the headers are part of firmware interface and need to be __packed.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20210621193756.134027-2-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index 18e49479d8b0..96f4e59c32a5 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -1726,12 +1726,15 @@ nortpm:
 	return rets;
 }
 
-static inline u8 mei_ext_hdr_set_vtag(struct mei_ext_hdr *ext, u8 vtag)
+static inline u8 mei_ext_hdr_set_vtag(void *ext, u8 vtag)
 {
-	ext->type = MEI_EXT_HDR_VTAG;
-	ext->ext_payload[0] = vtag;
-	ext->length = mei_data2slots(sizeof(*ext));
-	return ext->length;
+	struct mei_ext_hdr_vtag *vtag_hdr = ext;
+
+	vtag_hdr->hdr.type = MEI_EXT_HDR_VTAG;
+	vtag_hdr->hdr.length = mei_data2slots(sizeof(*vtag_hdr));
+	vtag_hdr->vtag = vtag;
+	vtag_hdr->reserved = 0;
+	return vtag_hdr->hdr.length;
 }
 
 /**
@@ -1745,7 +1748,6 @@ static struct mei_msg_hdr *mei_msg_hdr_init(const struct mei_cl_cb *cb)
 {
 	size_t hdr_len;
 	struct mei_ext_meta_hdr *meta;
-	struct mei_ext_hdr *ext;
 	struct mei_msg_hdr *mei_hdr;
 	bool is_ext, is_vtag;
 
@@ -1764,7 +1766,7 @@ static struct mei_msg_hdr *mei_msg_hdr_init(const struct mei_cl_cb *cb)
 
 	hdr_len += sizeof(*meta);
 	if (is_vtag)
-		hdr_len += sizeof(*ext);
+		hdr_len += sizeof(struct mei_ext_hdr_vtag);
 
 setup_hdr:
 	mei_hdr = kzalloc(hdr_len, GFP_KERNEL);