[PATCH 5.11 569/601] bnxt_en: Fix RX consumer index logic in the error path.

Greg Kroah-Hartman
2021-05-12T17:57:57Z

From: Michael Chan <michael.chan@broadcom.com>

[ Upstream commit bbd6f0a948139970f4a615dff189d9a503681a39 ]

In bnxt_rx_pkt(), the RX buffers are expected to complete in order.
If the RX consumer index indicates an out of order buffer completion,
it means we are hitting a hardware bug and the driver will abort all
remaining RX packets and reset the RX ring. The RX consumer index
that we pass to bnxt_discard_rx() is not correct. We should be
passing the current index (tmp_raw_cons) instead of the old index
(raw_cons). This bug can cause us to be at the wrong index when
trying to abort the next RX packet. It can crash like this:

#0 [ffff9bbcdf5c39a8] machine_kexec at ffffffff9b05e007
#1 [ffff9bbcdf5c3a00] __crash_kexec at ffffffff9b111232
#2 [ffff9bbcdf5c3ad0] panic at ffffffff9b07d61e
#3 [ffff9bbcdf5c3b50] oops_end at ffffffff9b030978
#4 [ffff9bbcdf5c3b78] no_context at ffffffff9b06aaf0
#5 [ffff9bbcdf5c3bd8] __bad_area_nosemaphore at ffffffff9b06ae2e
#6 [ffff9bbcdf5c3c28] bad_area_nosemaphore at ffffffff9b06af24
#7 [ffff9bbcdf5c3c38] __do_page_fault at ffffffff9b06b67e
#8 [ffff9bbcdf5c3cb0] do_page_fault at ffffffff9b06bb12
#9 [ffff9bbcdf5c3ce0] page_fault at ffffffff9bc015c5
[exception RIP: bnxt_rx_pkt+237]
RIP: ffffffffc0259cdd RSP: ffff9bbcdf5c3d98 RFLAGS: 00010213
RAX: 000000005dd8097f RBX: ffff9ba4cb11b7e0 RCX: ffffa923cf6e9000
RDX: 0000000000000fff RSI: 0000000000000627 RDI: 0000000000001000
RBP: ffff9bbcdf5c3e60 R8: 0000000000420003 R9: 000000000000020d
R10: ffffa923cf6ec138 R11: ffff9bbcdf5c3e83 R12: ffff9ba4d6f928c0
R13: ffff9ba4cac28080 R14: ffff9ba4cb11b7f0 R15: ffff9ba4d5a30000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018

Fixes: a1b0e4e684e9 ("bnxt_en: Improve RX consumer index validity check.")
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 11839f086f29..f3c659bc6bb6 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1731,14 +1731,16 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_cp_ring_info *cpr,

cons = rxcmp->rx_cmp_opaque;
if (unlikely(cons != rxr->rx_next_cons)) {
- int rc1 = bnxt_discard_rx(bp, cpr, raw_cons, rxcmp);
+ int rc1 = bnxt_discard_rx(bp, cpr, &tmp_raw_cons, rxcmp);

/* 0xffff is forced error, don't print it */
if (rxr->rx_next_cons != 0xffff)
netdev_warn(bp->dev, "RX cons %x != expected cons %x\n",
cons, rxr->rx_next_cons);
bnxt_sched_reset(bp, rxr);
- return rc1;
+ if (rc1)
+ return rc1;
+ goto next_rx_no_prod_no_len;
}
rx_buf = &rxr->rx_buf_ring[cons];
data = rx_buf->data;
--
2.30.2