[PATCH net-next 1/3] net: rmnet: annotate data-races around port->data_format
From: Eric Dumazet <edumazet@google.com>
Date: 2026-09-16 13:22:35
Subsystem:
networking drivers, qualcomm rmnet driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Subash Abhinov Kasiviswanathan, Sean Tranchetti, Linus Torvalds
port->data_format is written under RTNL from rmnet_newlink() and rmnet_changelink(), but it is read from the data path without any lock, both from RX (rmnet_rx_handler() context) and TX (rmnet_egress_handler() context). Note that rmnet_newlink() can be called for a real_dev which is already hooked to rmnet: the rx_handler is live and traffic can already be flowing when port->data_format is overwritten. Add the missing READ_ONCE()/WRITE_ONCE() annotations. While at it, sample port->data_format only once per packet and pass the value down, so that all the decisions taken for a given packet are based on a single consistent value. Otherwise the two ends of a packet transformation could disagree. On TX, rmnet_map_egress_handler() sized the headroom from one read while rmnet_map_add_map_header() decided on MAP_NEXT_HEADER_FLAG from another one, so a concurrent rmnet_changelink() could produce a MAP header announcing a v5 csum header that was neither reserved nor written. On RX, rmnet_map_validate_packet_len() and __rmnet_map_ingress_handler() could likewise disagree on the expected layout, and rmnet_map_send_ack() could trim a dl csum trailer that the ingress path never accounted for. rmnet_map_add_map_header(), rmnet_map_command(), rmnet_map_deaggregate(), rmnet_map_send_ack(), rmnet_map_validate_packet_len() and __rmnet_map_ingress_handler() therefore get the value from their caller instead of re-reading it. rmnet_changelink() now computes the new value in a local variable and publishes it with a single store, instead of letting the data path observe the intermediate (old_data_format & ~flags->mask) value. rmnet_vnd_headroom() is left alone, all its callers hold RTNL. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Subash Abhinov Kasiviswanathan <subash.a.kasiviswanathan@oss.qualcomm.com> Cc: Sean Tranchetti <sean.tranchetti@oss.qualcomm.com> --- .../ethernet/qualcomm/rmnet/rmnet_config.c | 10 +++--- .../ethernet/qualcomm/rmnet/rmnet_handlers.c | 32 +++++++++++-------- .../net/ethernet/qualcomm/rmnet/rmnet_map.h | 9 +++--- .../qualcomm/rmnet/rmnet_map_command.c | 9 +++--- .../ethernet/qualcomm/rmnet/rmnet_map_data.c | 14 ++++---- 5 files changed, 42 insertions(+), 32 deletions(-)
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index bed6f63facf250bd1f8d07d09f7715918421a88d..59ef8b4ce5321ebbd1d416fd9da0a820e53ecf9e 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c@@ -176,7 +176,7 @@ static int rmnet_newlink(struct net_device *dev, } netdev_dbg(dev, "data format [0x%08X]\n", data_format); - port->data_format = data_format; + WRITE_ONCE(port->data_format, data_format); return 0;
@@ -342,14 +342,16 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[], if (data[IFLA_RMNET_FLAGS]) { struct ifla_rmnet_flags *flags; u32 old_data_format; + u32 data_format; old_data_format = port->data_format; flags = nla_data(data[IFLA_RMNET_FLAGS]); - port->data_format &= ~flags->mask; - port->data_format |= flags->flags & flags->mask; + data_format = old_data_format & ~flags->mask; + data_format |= flags->flags & flags->mask; + WRITE_ONCE(port->data_format, data_format); if (rmnet_vnd_update_dev_mtu(port, real_dev)) { - port->data_format = old_data_format; + WRITE_ONCE(port->data_format, old_data_format); NL_SET_ERR_MSG_MOD(extack, "Invalid MTU on real dev"); return -EINVAL; }
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index d055a2628d8c9d0b6e7e85eb98f6fa9b5a1bd531..d4fec2fff227cd93f14eb1802aff185e6d496786 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c@@ -54,7 +54,8 @@ rmnet_deliver_skb(struct sk_buff *skb) static void __rmnet_map_ingress_handler(struct sk_buff *skb, - struct rmnet_port *port) + struct rmnet_port *port, + u32 data_format) { struct rmnet_map_header *map_header = (void *)skb->data; struct rmnet_endpoint *ep;
@@ -63,8 +64,8 @@ __rmnet_map_ingress_handler(struct sk_buff *skb, if (map_header->flags & MAP_CMD_FLAG) { /* Packet contains a MAP command (not data) */ - if (port->data_format & RMNET_FLAGS_INGRESS_MAP_COMMANDS) - return rmnet_map_command(skb, port); + if (data_format & RMNET_FLAGS_INGRESS_MAP_COMMANDS) + return rmnet_map_command(skb, port, data_format); goto free_skb; }
@@ -82,7 +83,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb, skb->dev = ep->egress_dev; - if ((port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) && + if ((data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) && (map_header->flags & MAP_NEXT_HEADER_FLAG)) { if (rmnet_map_process_next_hdr_packet(skb, len)) goto free_skb;
@@ -92,7 +93,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb, /* Subtract MAP header */ skb_pull(skb, sizeof(*map_header)); rmnet_set_skb_proto(skb); - if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4 && + if (data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4 && !rmnet_map_checksum_downlink_packet(skb, len + pad)) skb->ip_summed = CHECKSUM_UNNECESSARY; }
@@ -110,6 +111,7 @@ rmnet_map_ingress_handler(struct sk_buff *skb, struct rmnet_port *port) { struct sk_buff *skbn; + u32 data_format; if (skb->dev->type == ARPHRD_ETHER) { if (pskb_expand_head(skb, ETH_HLEN, 0, GFP_ATOMIC)) {
@@ -120,14 +122,16 @@ rmnet_map_ingress_handler(struct sk_buff *skb, skb_push(skb, ETH_HLEN); } - if (port->data_format & RMNET_FLAGS_INGRESS_DEAGGREGATION) { - while ((skbn = rmnet_map_deaggregate(skb, port)) != NULL) - __rmnet_map_ingress_handler(skbn, port); + data_format = READ_ONCE(port->data_format); + + if (data_format & RMNET_FLAGS_INGRESS_DEAGGREGATION) { + while ((skbn = rmnet_map_deaggregate(skb, data_format)) != NULL) + __rmnet_map_ingress_handler(skbn, port, data_format); consume_skb(skb); } else { - if (rmnet_map_validate_packet_len(skb, port)) - __rmnet_map_ingress_handler(skb, port); + if (rmnet_map_validate_packet_len(skb, data_format)) + __rmnet_map_ingress_handler(skb, port, data_format); else kfree_skb(skb); }
@@ -139,14 +143,16 @@ static int rmnet_map_egress_handler(struct sk_buff *skb, { int required_headroom, additional_header_len, csum_type = 0; struct rmnet_map_header *map_header; + u32 data_format; additional_header_len = 0; required_headroom = sizeof(struct rmnet_map_header); - if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV4) { + data_format = READ_ONCE(port->data_format); + if (data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV4) { additional_header_len = sizeof(struct rmnet_map_ul_csum_header); csum_type = RMNET_FLAGS_EGRESS_MAP_CKSUMV4; - } else if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) { + } else if (data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) { additional_header_len = sizeof(struct rmnet_map_v5_csum_header); csum_type = RMNET_FLAGS_EGRESS_MAP_CKSUMV5; }
@@ -161,7 +167,7 @@ static int rmnet_map_egress_handler(struct sk_buff *skb, csum_type); map_header = rmnet_map_add_map_header(skb, additional_header_len, - port, 0); + data_format, 0); if (!map_header) return -ENOMEM;
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 60ca8b780c88ad7d9a6334370c0ff73a83e02d2d..0977e495f5915539fc1154bb592a2648aef43cda 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h@@ -41,12 +41,13 @@ enum rmnet_map_commands { #define RMNET_MAP_ADD_PAD_BYTES 1 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb, - struct rmnet_port *port); + u32 data_format); struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, int hdrlen, - struct rmnet_port *port, + u32 data_format, int pad); -void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port); +void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port, + u32 data_format); int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len); void rmnet_map_checksum_uplink_packet(struct sk_buff *skb, struct rmnet_port *port,
@@ -59,6 +60,6 @@ void rmnet_map_tx_aggregate_init(struct rmnet_port *port); void rmnet_map_tx_aggregate_exit(struct rmnet_port *port); void rmnet_map_update_ul_agg_config(struct rmnet_port *port, u32 size, u32 count, u32 time); -u32 rmnet_map_validate_packet_len(struct sk_buff *skb, struct rmnet_port *port); +u32 rmnet_map_validate_packet_len(struct sk_buff *skb, u32 data_format); #endif /* _RMNET_MAP_H_ */
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c
index add0f5ade2e6174427abff532d160f89122059f7..d334727e1f5256201996fc56c419ec05f04dde4e 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c@@ -48,13 +48,13 @@ static u8 rmnet_map_do_flow_control(struct sk_buff *skb, static void rmnet_map_send_ack(struct sk_buff *skb, unsigned char type, - struct rmnet_port *port) + u32 data_format) { struct rmnet_map_header *map_header = (void *)skb->data; struct rmnet_map_control_command *cmd; struct net_device *dev = skb->dev; - if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) + if (data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) skb_trim(skb, skb->len - sizeof(struct rmnet_map_dl_csum_trailer));
@@ -72,7 +72,8 @@ static void rmnet_map_send_ack(struct sk_buff *skb, /* Process MAP command frame and send N/ACK message as appropriate. Message cmd * name is decoded here and appropriate handler is called. */ -void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port) +void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port, + u32 data_format) { struct rmnet_map_header *map_header = (void *)skb->data; struct rmnet_map_control_command *cmd;
@@ -98,5 +99,5 @@ void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port) break; } if (rc == RMNET_MAP_COMMAND_ACK) - rmnet_map_send_ack(skb, rc, port); + rmnet_map_send_ack(skb, rc, data_format); }
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index e6f48dc9fe64d7e563a0ba355c1ede35c73b4593..39d6d084e73f00f9fcd475ad98b16dde4cb266c6 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c@@ -294,7 +294,7 @@ static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb, */ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, int hdrlen, - struct rmnet_port *port, + u32 data_format, int pad) { struct rmnet_map_header *map_header;
@@ -306,7 +306,7 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, memset(map_header, 0, sizeof(struct rmnet_map_header)); /* Set next_hdr bit for csum offload packets */ - if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) + if (data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) map_header->flags |= MAP_NEXT_HEADER_FLAG; if (pad == RMNET_MAP_NO_PAD_BYTES) {
@@ -333,7 +333,7 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, return map_header; } -u32 rmnet_map_validate_packet_len(struct sk_buff *skb, struct rmnet_port *port) +u32 rmnet_map_validate_packet_len(struct sk_buff *skb, u32 data_format) { struct rmnet_map_v5_csum_header *next_hdr = NULL; struct rmnet_map_header *maph;
@@ -351,9 +351,9 @@ u32 rmnet_map_validate_packet_len(struct sk_buff *skb, struct rmnet_port *port) packet_len = ntohs(maph->pkt_len) + sizeof(*maph); - if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) { + if (data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) { packet_len += sizeof(struct rmnet_map_dl_csum_trailer); - } else if ((port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) && + } else if ((data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) && !(maph->flags & MAP_CMD_FLAG)) { /* Mapv5 data pkt without csum hdr is invalid */ if (!(maph->flags & MAP_NEXT_HEADER_FLAG))
@@ -381,12 +381,12 @@ u32 rmnet_map_validate_packet_len(struct sk_buff *skb, struct rmnet_port *port) * is responsible for freeing the original skb. */ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb, - struct rmnet_port *port) + u32 data_format) { struct sk_buff *skbn; u32 packet_len; - packet_len = rmnet_map_validate_packet_len(skb, port); + packet_len = rmnet_map_validate_packet_len(skb, data_format); if (!packet_len) return NULL;
--
2.55.0.1032.g73a4cd73de-goog