From 5db89c99566fc4728cc92e941d8e1975711e24b5 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Wed, 13 May 2026 21:37:39 -0400 Subject: [PATCH] net: ifb: report ethtool stats over num_tx_queues ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues entries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB per-queue RX and TX stats live in those entries: ifb_xmit() updates txp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates txp->tx_stats, and ifb_stats64() aggregates both over dev->num_tx_queues. The ethtool stats callbacks instead size and walk the per-queue stats with dev->real_num_rx_queues and dev->real_num_tx_queues. With an asymmetric device where the RX queue count exceeds the TX queue count, for example: ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb ethtool -S ifb10 ifb_get_ethtool_stats() indexes past the tx_private allocation and copies adjacent slab data through ETHTOOL_GSTATS. Use dev->num_tx_queues consistently for the stats strings, the stats count, and the stats data walks. This reports one RX stats group and one TX stats group for each backing ifb_q_private entry, which is the queue set IFB can actually populate. Reproduced under UML+KASAN at v7.1-rc2: BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae Read of size 8 at addr 0000000062dbd228 by task ethtool/36 ifb_fill_stats_data+0x3c/0xae ifb_get_ethtool_stats+0xc0/0x129 __dev_ethtool+0x1ca5/0x363c dev_ethtool+0x123/0x1b3 dev_ioctl+0x56c/0x744 sock_do_ioctl+0x15f/0x1b2 sock_ioctl+0x4d5/0x50a sys_ioctl+0xd8b/0xde9 With the patch applied, the same UML+KASAN repro is silent and ethtool -S ifb10 reports only the stats backed by the single allocated tx_private entry. Fixes: a21ee5b2fcb8 ("net: ifb: support ethtools stats") Cc: stable@vger.kernel.org Signed-off-by: Michael Bommarito Link: https://patch.msgid.link/20260514013739.3549624-1-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/ifb.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c index 5407d2ed71b3..43aa1bfd41cf 100644 --- a/drivers/net/ifb.c +++ b/drivers/net/ifb.c @@ -211,12 +211,12 @@ static void ifb_get_strings(struct net_device *dev, u32 stringset, u8 *buf) switch (stringset) { case ETH_SS_STATS: - for (i = 0; i < dev->real_num_rx_queues; i++) + for (i = 0; i < dev->num_tx_queues; i++) for (j = 0; j < IFB_Q_STATS_LEN; j++) ethtool_sprintf(&p, "rx_queue_%u_%.18s", i, ifb_q_stats_desc[j].desc); - for (i = 0; i < dev->real_num_tx_queues; i++) + for (i = 0; i < dev->num_tx_queues; i++) for (j = 0; j < IFB_Q_STATS_LEN; j++) ethtool_sprintf(&p, "tx_queue_%u_%.18s", i, ifb_q_stats_desc[j].desc); @@ -229,8 +229,7 @@ static int ifb_get_sset_count(struct net_device *dev, int sset) { switch (sset) { case ETH_SS_STATS: - return IFB_Q_STATS_LEN * (dev->real_num_rx_queues + - dev->real_num_tx_queues); + return IFB_Q_STATS_LEN * dev->num_tx_queues * 2; default: return -EOPNOTSUPP; } @@ -262,12 +261,12 @@ static void ifb_get_ethtool_stats(struct net_device *dev, struct ifb_q_private *txp; int i; - for (i = 0; i < dev->real_num_rx_queues; i++) { + for (i = 0; i < dev->num_tx_queues; i++) { txp = dp->tx_private + i; ifb_fill_stats_data(&data, &txp->rx_stats); } - for (i = 0; i < dev->real_num_tx_queues; i++) { + for (i = 0; i < dev->num_tx_queues; i++) { txp = dp->tx_private + i; ifb_fill_stats_data(&data, &txp->tx_stats); }