mt7925_usb_sdio_tx_prepare_skb() pushes a TX descriptor and a USB
header onto every skb and assumes the headroom for them is already
there. That holds for locally generated traffic, where mac80211
reserves hw->extra_tx_headroom, but forwarded frames are sent through
ieee80211_8023_xmit(), which does not reserve it. Bridge a wired
interface to an mt7925u AP and the first forwarded frame that arrives
short panics the kernel:
skbuff: skb_under_panic: len:415 put:4 tail:0x19b end:0x640 dev:wlan1
kernel BUG at net/core/skbuff.c:212!
Call trace:
skb_panic+0x58/0x60 (P)
skb_push+0x58/0x60
mt7925_usb_sdio_tx_prepare_skb+0xf8/0x1b8 [mt7925_common]
mt76u_tx_queue_skb+0xa0/0x1f8 [mt76_usb]
__mt76_tx_queue_skb+0x54/0xe8 [mt76]
mt76_txq_schedule.part.0+0x204/0x478 [mt76]
mt76_txq_schedule_all+0x50/0x80 [mt76]
mt792x_tx_worker+0x68/0x100 [mt792x_lib]
__mt76_worker_fn+0x84/0x150 [mt76]
Whether a given setup hits it depends on how much headroom the ingress
netdev leaves in its rx skbs. Reproduced on a Raspberry Pi 5 bridging
onboard ethernet to a Netgear A9000; originally reported on an MT7986
router running OpenWrt. Nick Morrow's testing on a Pi 4 (bcmgenet),
which leaves more headroom, helped narrow the trigger to the ingress
path.
The same bug was fixed on mt7921 by commit 98c4d0abf5c4 ("mt76:
mt7921: don't assume adequate headroom for SDIO headers"), but mt7925
was copied from mt7921 without the fix. Add the same guard here.
Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips")
Cc: [email protected]
Link: https://github.com/morrownr/mt76/issues/52
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
mt76_npu_device_active() and mt76_ppe_device_active() read dev->mmio.npu
and dev->mmio.ppe_dev. The mmio, usb and sdio bus structs share a union in
struct mt76_dev, so on USB and SDIO these read unrelated data from the
usb/sdio struct, which is non-NULL in practice.
mt76_npu_device_active() then returns true on USB, and
mt76_rx_poll_complete() takes the offload path and skips
mt76_rx_aggr_reorder(). RX A-MPDU subframes are delivered out of order and
the peer's TCP stack treats that as loss: heavy retransmissions and reduced
throughput in AP mode. Seen on mt7921u, mt7925u, mt76x2u and mt76x0u.
Gate both helpers on mt76_is_mmio() so they only run for the bus type that
owns the mmio union member.
Fixes: 7fb554b1b623 ("wifi: mt76: Introduce the NPU generic layer")
Cc: [email protected]
Tested-by: Nick Morrow <[email protected]>
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7615_rx_check() and
mt7615_queue_rx_skb() dispatch it to mt7615_mac_tx_free() on every bus.
mt7615_mac_tx_free() cleans the DMA tx queues with
mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the
mmio queue ops implement that callback; on the mt7663 USB and SDIO
buses it is NULL, so a TXRX_NOTIFY there calls a NULL pointer in the RX
worker. Same defect as the mt7921 and mt7925 patches in this series.
Drop the event on non-mmio buses via mt76_is_mmio(), as in
commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for
non-mmio devices").
Fixes: eb99cc95c3b6 ("mt76: mt7615: introduce mt7663u support")
Cc: [email protected]
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7925_rx_check() and
mt7925_queue_rx_skb() dispatch it to mt7925_mac_tx_free() on every bus.
mt7925_mac_tx_free() cleans the DMA tx queues with
mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the
mmio queue ops implement that callback; on USB it is NULL, so a
TXRX_NOTIFY there calls a NULL pointer in the RX worker:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:0x0
Call Trace:
mt7925_mac_tx_free+0x58/0x350 [mt7925_common]
mt7925_rx_check+0xe2/0x130 [mt7925_common]
mt76u_rx_worker+0x1b9/0x620 [mt76_usb]
Drop the event on non-mmio buses via mt76_is_mmio(), as in
commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for
non-mmio devices").
Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips")
Cc: [email protected]
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7921_rx_check() and
mt7921_queue_rx_skb() dispatch it to mt7921_mac_tx_free() on every bus.
mt7921_mac_tx_free() cleans the DMA tx queues with
mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the
mmio queue ops implement that callback; on USB and SDIO it is NULL, so
a TXRX_NOTIFY there calls a NULL pointer in the RX worker:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:0x0
Call Trace:
mt7921_mac_tx_free+0x64/0x310 [mt7921_common]
mt7921_rx_check+0x5f/0xf0 [mt7921_common]
mt76u_rx_worker+0x1b9/0x620 [mt76_usb]
Drop the event on non-mmio buses via mt76_is_mmio(), as in
commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for
non-mmio devices").
Fixes: 48fab5bbef40 ("mt76: mt7921: introduce mt7921s support")
Cc: [email protected]
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
When the fcsfail filter is enabled the hardware passes frames with a bad
FCS up to the driver, but mt76x02_mac_process_rx() never checks
MT_RXINFO_CRCERR and hands them to mac80211 without
RX_FLAG_FAILED_FCS_CRC. In monitor mode the radiotap flags byte then
never gets IEEE80211_RADIOTAP_F_BADFCS set and corrupted frames cannot be
told apart from clean ones.
Set RX_FLAG_FAILED_FCS_CRC from the descriptor CRC error bit, matching
mt7603, mt7615, mt7915, mt7921, mt7925 and mt7996.
Reported-by: 0072a70 <[email protected]>
Closes: https://github.com/morrownr/mt76/issues/38
Tested-by: 0072a70 <[email protected]>
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
The MPDU length in the rx descriptor comes from the hardware. In
monitor mode with the fcsfail filter enabled, the hardware passes up
corrupted frames, and a corrupted frame can report a length larger
than the received buffer. The bounds check correctly discards such
frames, but its WARN_ON_ONCE wrapper means any over-the-air garbage
frame taints the kernel, and panics it on the first such frame when
panic_on_warn is set.
Drop the WARN and discard the frame silently, matching what
commit c2d4c8723dbf ("mt76x2: remove some harmless WARN_ONs in tx
status and rx path") did for the neighboring rx and tx status paths.
Observed immediately on rx with an MT7612U in fcsfail monitor mode
on a busy channel.
Fixes: 7bc04215a66b ("mt76: add driver code for MT76x2e")
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
mt7921_change_chanctx() configures the channel for monitor vifs but
does not re-assert sniffer mode. mt7925_change_chanctx() does. Match
mt7925 by adding the missing mt7921_mcu_set_sniffer(true) call,
completing the architectural pattern from commit 914189af23b8 ("wifi:
mt76: mt7921: fix channel switch fail in monitor mode").
The user-visible regression this asymmetry produced on v6.17 and v6.18
was addressed by commit cdb2941a516c ("Revert "wifi: mt76: mt792x:
improve monitor interface handling"") in v6.19 and backported to the
6.17.y and 6.18.y stable trees. This patch is defense in depth in
case the NO_VIRTUAL_MONITOR change is reintroduced in a future series.
Tested-by: Nick Morrow <[email protected]>
Tested-on: RasPi4B, RasPiOS 64 bit, Alfa AWUS036AXML mt7921u
Tested-on: RasPi4B, RasPiOS 64 bit, Netgear A9000 mt7925u
Signed-off-by: Devin Wittmayer <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Felix Fietkau <[email protected]>
