From: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
commit 1e9cb763e9bacf0c932aa948f50dcfca6f519a26 upstream.
The ENA adapters on our instances occasionally reset. Once recently
logged a UBSAN failure to console in the process:
UBSAN: shift-out-of-bounds in build/linux/drivers/net/ethernet/amazon/ena/ena_com.c:540:13
shift exponent 32 is too large for 32-bit type 'unsigned int'
CPU: 28 PID: 70012 Comm: kworker/u72:2 Kdump: loaded not tainted 5.15.117
Hardware name: Amazon EC2 c5d.9xlarge/, BIOS 1.0 10/16/2017
Workqueue: ena ena_fw_reset_device [ena]
Call Trace:
<TASK>
dump_stack_lvl+0x4a/0x63
dump_stack+0x10/0x16
ubsan_epilogue+0x9/0x36
__ubsan_handle_shift_out_of_bounds.cold+0x61/0x10e
? __const_udelay+0x43/0x50
ena_delay_exponential_backoff_us.cold+0x16/0x1e [ena]
wait_for_reset_state+0x54/0xa0 [ena]
ena_com_dev_reset+0xc8/0x110 [ena]
ena_down+0x3fe/0x480 [ena]
ena_destroy_device+0xeb/0xf0 [ena]
ena_fw_reset_device+0x30/0x50 [ena]
process_one_work+0x22b/0x3d0
worker_thread+0x4d/0x3f0
? process_one_work+0x3d0/0x3d0
kthread+0x12a/0x150
? set_kthread_struct+0x50/0x50
ret_from_fork+0x22/0x30
</TASK>
Apparently, the reset delays are getting so large they can trigger a
UBSAN panic.
Looking at the code, the current timeout is capped at 5000us. Using a
base value of 100us, the current code will overflow after (1<<29). Even
at values before 32, this function wraps around, perhaps
unintentionally.
Cap the value of the exponent used for this backoff at (1<<16) which is
larger than currently necessary, but large enough to support bigger
values in the future.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 4bb7f4cf60e3 ("net: ena: reduce driver load time")
Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Reviewed-by: Shay Agroskin <shayagr@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230711013621.GE1926@xxxxxxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/amazon/ena/ena_com.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -35,6 +35,8 @@
#define ENA_REGS_ADMIN_INTR_MASK 1
+#define ENA_MAX_BACKOFF_DELAY_EXP 16U
+
#define ENA_MIN_ADMIN_POLL_US 100
#define ENA_MAX_ADMIN_POLL_US 5000
@@ -522,6 +524,7 @@ static int ena_com_comp_status_to_errno(
static void ena_delay_exponential_backoff_us(u32 exp, u32 delay_us)
{
+ exp = min_t(u32, exp, ENA_MAX_BACKOFF_DELAY_EXP);
delay_us = max_t(u32, ENA_MIN_ADMIN_POLL_US, delay_us);
delay_us = min_t(u32, delay_us * (1U << exp), ENA_MAX_ADMIN_POLL_US);
usleep_range(delay_us, 2 * delay_us);
