Commit 6c95483b authored Jun 09, 2017 by Jag Raman Committed by David S. Miller Jun 10, 2017

sparc64: ldc abort during vds iso boot



Orabug: 20902628

When an ldc control-only packet is received during data exchange in
read_nonraw(), a new rx head is calculated but the rx queue head is not
actually advanced (rx_set_head() is not called) and a branch is taken to
'no_data' at which point two things can happen depending on the value
of the newly calculated rx head and the current rx tail:

- If the rx queue is determined to be not empty, then the wrong packet
  is picked up.

- If the rx queue is determined to be empty, then a read error (EAGAIN)
  is eventually returned since it is falsely assumed that more data was
  expected.

The fix is to update the rx head and return in case of a control only
packet during data exchange.

Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Aaron Young <aaron.young@oracle.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent fc43b978

arch/sparc/kernel/ldc.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -1778,9 +1778,14 @@ static int read_nonraw(struct ldc_channel lp, void buf, unsigned int size)

		lp->rcv_nxt = p->seqid;

		/*
		* If this is a control-only packet, there is nothing
		* else to do but advance the rx queue since the packet
		* was already processed above.
		*/
		if (!(p->type & LDC_DATA)) {
		new = rx_advance(lp, new);
		goto no_data;
		break;
		}
		if (p->stype & (LDC_ACK \| LDC_NACK)) {
		err = data_ack_nack(lp, p);

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