3.18-stable review patch. If anyone has any objections, please let me know.
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From: Jag Raman jag.raman@oracle.com
[ Upstream commit 6c95483b768c62f8ee933ae08a1bdbcb78b5410f ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/sparc/kernel/ldc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/sparc/kernel/ldc.c +++ b/arch/sparc/kernel/ldc.c @@ -1693,9 +1693,14 @@ static int read_nonraw(struct ldc_channe
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);