[PATCH 1/1] block: sed-opal: handle empty atoms when parsing response

[gjoyce@linux.ibm.com]

From: Greg Joyce <gjoyce@linux.ibm.com>

The SED Opal response parsing function response_parse() does not
handle the case of an empty atom in the response. This causes
the entry count to be too high and the response fails to be
parsed. Recognizing, but ignoring, empty atoms allows response
handling to succeed.

Signed-off-by: Greg Joyce <gjoyce@linux.ibm.com>
---
 block/opal_proto.h | 1 +
 block/sed-opal.c   | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/opal_proto.h b/block/opal_proto.h
index dec7ce3a3edb..d247a457bf6e 100644
--- a/block/opal_proto.h
+++ b/block/opal_proto.h
@@ -71,6 +71,7 @@ enum opal_response_token {
 #define SHORT_ATOM_BYTE  0xBF
 #define MEDIUM_ATOM_BYTE 0xDF
 #define LONG_ATOM_BYTE   0xE3
+#define EMPTY_ATOM_BYTE  0xFF
 
 #define OPAL_INVAL_PARAM 12
 #define OPAL_MANUFACTURED_INACTIVE 0x08
diff --git a/block/sed-opal.c b/block/sed-opal.c
index 3d9e9cd250bd..fa4dba5d8531 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -1056,16 +1056,20 @@ static int response_parse(const u8 *buf, size_t length,
 			token_length = response_parse_medium(iter, pos);
 		else if (pos[0] <= LONG_ATOM_BYTE) /* long atom */
 			token_length = response_parse_long(iter, pos);
+		else if (pos[0] == EMPTY_ATOM_BYTE) /* empty atom */
+			token_length = 1;
 		else /* TOKEN */
 			token_length = response_parse_token(iter, pos);
 
 		if (token_length < 0)
 			return token_length;
 
+		if (pos[0] != EMPTY_ATOM_BYTE)
+			num_entries++;
+
 		pos += token_length;
 		total -= token_length;
 		iter++;
-		num_entries++;
 	}
 
 	resp->num = num_entries;
-- 
gjoyce@linux.ibm.com