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@xxxxxxxxxx>
Reviewed-by: Aaron Young <aaron.young@xxxxxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Reviewed-by: Bijan Mottahedeh <bijan.mottahedeh@xxxxxxxxxx>
Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
---
arch/sparc/kernel/ldc.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/arch/sparc/kernel/ldc.c b/arch/sparc/kernel/ldc.c
index 639da7b..47817b7 100644
--- a/arch/sparc/kernel/ldc.c
+++ b/arch/sparc/kernel/ldc.c
@@ -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);
--
1.7.1
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