* [PATCH net] can: kvaser_pciefd: refine error prone echo_skb_max handling logic
[not found] <20250529075313.1101820-1-mkl@pengutronix.de>
@ 2025-05-29 7:49 ` Marc Kleine-Budde
2025-05-29 11:00 ` patchwork-bot+netdevbpf
0 siblings, 1 reply; 2+ messages in thread
From: Marc Kleine-Budde @ 2025-05-29 7:49 UTC (permalink / raw)
To: netdev
Cc: davem, kuba, linux-can, kernel, Fedor Pchelkin, stable,
Marc Kleine-Budde
From: Fedor Pchelkin <pchelkin@ispras.ru>
echo_skb_max should define the supported upper limit of echo_skb[]
allocated inside the netdevice's priv. The corresponding size value
provided by this driver to alloc_candev() is KVASER_PCIEFD_CAN_TX_MAX_COUNT
which is 17.
But later echo_skb_max is rounded up to the nearest power of two (for the
max case, that would be 32) and the tx/ack indices calculated further
during tx/rx may exceed the upper array boundary. Kasan reported this for
the ack case inside kvaser_pciefd_handle_ack_packet(), though the xmit
function has actually caught the same thing earlier.
BUG: KASAN: slab-out-of-bounds in kvaser_pciefd_handle_ack_packet+0x2d7/0x92a drivers/net/can/kvaser_pciefd.c:1528
Read of size 8 at addr ffff888105e4f078 by task swapper/4/0
CPU: 4 UID: 0 PID: 0 Comm: swapper/4 Not tainted 6.15.0 #12 PREEMPT(voluntary)
Call Trace:
<IRQ>
dump_stack_lvl lib/dump_stack.c:122
print_report mm/kasan/report.c:521
kasan_report mm/kasan/report.c:634
kvaser_pciefd_handle_ack_packet drivers/net/can/kvaser_pciefd.c:1528
kvaser_pciefd_read_packet drivers/net/can/kvaser_pciefd.c:1605
kvaser_pciefd_read_buffer drivers/net/can/kvaser_pciefd.c:1656
kvaser_pciefd_receive_irq drivers/net/can/kvaser_pciefd.c:1684
kvaser_pciefd_irq_handler drivers/net/can/kvaser_pciefd.c:1733
__handle_irq_event_percpu kernel/irq/handle.c:158
handle_irq_event kernel/irq/handle.c:210
handle_edge_irq kernel/irq/chip.c:833
__common_interrupt arch/x86/kernel/irq.c:296
common_interrupt arch/x86/kernel/irq.c:286
</IRQ>
Tx max count definitely matters for kvaser_pciefd_tx_avail(), but for seq
numbers' generation that's not the case - we're free to calculate them as
would be more convenient, not taking tx max count into account. The only
downside is that the size of echo_skb[] should correspond to the max seq
number (not tx max count), so in some situations a bit more memory would
be consumed than could be.
Thus make the size of the underlying echo_skb[] sufficient for the rounded
max tx value.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 8256e0ca6010 ("can: kvaser_pciefd: Fix echo_skb race")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Link: https://patch.msgid.link/20250528192713.63894-1-pchelkin@ispras.ru
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
drivers/net/can/kvaser_pciefd.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/can/kvaser_pciefd.c b/drivers/net/can/kvaser_pciefd.c
index 7d3066691d5d..52301511ed1b 100644
--- a/drivers/net/can/kvaser_pciefd.c
+++ b/drivers/net/can/kvaser_pciefd.c
@@ -966,7 +966,7 @@ static int kvaser_pciefd_setup_can_ctrls(struct kvaser_pciefd *pcie)
u32 status, tx_nr_packets_max;
netdev = alloc_candev(sizeof(struct kvaser_pciefd_can),
- KVASER_PCIEFD_CAN_TX_MAX_COUNT);
+ roundup_pow_of_two(KVASER_PCIEFD_CAN_TX_MAX_COUNT));
if (!netdev)
return -ENOMEM;
@@ -995,7 +995,6 @@ static int kvaser_pciefd_setup_can_ctrls(struct kvaser_pciefd *pcie)
can->tx_max_count = min(KVASER_PCIEFD_CAN_TX_MAX_COUNT, tx_nr_packets_max - 1);
can->can.clock.freq = pcie->freq;
- can->can.echo_skb_max = roundup_pow_of_two(can->tx_max_count);
spin_lock_init(&can->lock);
can->can.bittiming_const = &kvaser_pciefd_bittiming_const;
base-commit: 271683bb2cf32e5126c592b5d5e6a756fa374fd9
--
2.47.2
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