[PATCH 146/173] repair gdbstub to match the gdbserial protocol specification

[Willy Tarreau]

2.6.27.59-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>

commit fb82c0ff27b2c40c6f7a3d1a94cafb154591fa80 upstream.

The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.

The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.

The incorrect response from the gdbstub leads the debugger clients to
not function correctly.  Recent versions of gdb will not detach correctly as a result of this behavior.

Backport-request-by: Frank Pan <frankpzh@xxxxxxxxx>
Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Signed-off-by: Dongdong Deng <dongdong.deng@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>


---
 kernel/kgdb.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1001,10 +1001,8 @@ static void gdb_cmd_query(struct kgdb_st
 	switch (remcom_in_buffer[1]) {
 	case 's':
 	case 'f':
-		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
-			error_packet(remcom_out_buffer, -EINVAL);
+		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
 			break;
-		}
 
 		i = 0;
 		remcom_out_buffer[0] = 'm';
@@ -1045,10 +1043,9 @@ static void gdb_cmd_query(struct kgdb_st
 		pack_threadid(remcom_out_buffer + 2, thref);
 		break;
 	case 'T':
-		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
-			error_packet(remcom_out_buffer, -EINVAL);
+		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
 			break;
-		}
+
 		ks->threadid = 0;
 		ptr = remcom_in_buffer + 17;
 		kgdb_hex2long(&ptr, &ks->threadid);


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