From: Feng Liu Date: Tue, 30 Jun 2026 11:51:49 +0000 (+0300) Subject: net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation X-Git-Tag: v7.2-rc3~29^2~29^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=25f6b929c7e379cbea7cb8caa67b49b2d1efae17;p=thirdparty%2Fkernel%2Flinux.git net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation mlx5e_hv_vhca_stats_create() is called from mlx5e_nic_enable(), before mlx5e_open(). At that point priv->stats_nch is still zero, because it is only ever incremented in mlx5e_channel_stats_alloc(), which is reached only from mlx5e_open_channel(). mlx5e_hv_vhca_stats_buf_size() therefore returns 0, and kvzalloc(0, GFP_KERNEL) returns ZERO_SIZE_PTR ((void *)16) rather than NULL. The "if (!buf)" guard does not catch this, and mlx5e_hv_vhca_stats_create() completes "successfully" with priv->stats_agent.buf set to ZERO_SIZE_PTR. Once channels are opened (priv->stats_nch > 0) and the hypervisor enables stats reporting, mlx5e_hv_vhca_stats_work() recomputes buf_len using the new non-zero stats_nch and calls memset(buf, 0, buf_len) on ZERO_SIZE_PTR, faulting at address 0x10. Allocate the buffer based on priv->max_nch, which is set in mlx5e_priv_init() and is the upper bound on stats_nch: - Add a separate helper mlx5e_hv_vhca_stats_buf_max_size() that returns sizeof(per_ring_stats) * max(max_nch, stats_nch), and use it for the kvzalloc() in mlx5e_hv_vhca_stats_create(). - Keep mlx5e_hv_vhca_stats_buf_size() (which returns based on stats_nch) for the worker's active payload size, so the wire format (block->rings = stats_nch) and the amount of data filled by mlx5e_hv_vhca_fill_stats() are unchanged. The max(max_nch, stats_nch) guard handles the rare case where mlx5e_attach_netdev() recomputes max_nch downward across a detach/resume cycle while priv->stats_nch persists (mlx5e_detach_netdev does not call mlx5e_priv_cleanup, so stats_nch is only reset when the netdev is destroyed). Without the guard, the worker could compute buf_len from stats_nch and overrun the smaller buffer allocated based on the reduced max_nch. Allocating a non-zero buffer also makes the kvzalloc() failure path in mlx5e_hv_vhca_stats_create() reachable for the first time: it returns early without (re)creating the agent. Clear priv->stats_agent.{agent,buf} in mlx5e_hv_vhca_stats_destroy() after freeing them, so that if a later create() bails out on this path, a subsequent teardown does not double-free the stale agent/buffer left from a previous enable/disable cycle. This mirrors the existing mlx5e pattern of preallocating arrays of size max_nch (e.g. priv->channel_stats) and lazily populating entries up to stats_nch on demand. Fixes: fa691d0c9c08 ("net/mlx5e: Allocate per-channel stats dynamically at first usage") Signed-off-by: Feng Liu Reviewed-by: Eran Ben Elisha Signed-off-by: Tariq Toukan Link: https://patch.msgid.link/20260630115151.729219-2-tariqt@nvidia.com Signed-off-by: Paolo Abeni --- diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c b/drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c index 195863b2c013..72f3ca4dd076 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c @@ -54,6 +54,12 @@ static int mlx5e_hv_vhca_stats_buf_size(struct mlx5e_priv *priv) priv->stats_nch); } +static int mlx5e_hv_vhca_stats_buf_max_size(struct mlx5e_priv *priv) +{ + return (sizeof(struct mlx5e_hv_vhca_per_ring_stats) * + max(priv->max_nch, priv->stats_nch)); +} + static void mlx5e_hv_vhca_stats_work(struct work_struct *work) { struct mlx5e_hv_vhca_stats_agent *sagent; @@ -122,7 +128,7 @@ static void mlx5e_hv_vhca_stats_cleanup(struct mlx5_hv_vhca_agent *agent) void mlx5e_hv_vhca_stats_create(struct mlx5e_priv *priv) { - int buf_len = mlx5e_hv_vhca_stats_buf_size(priv); + int buf_len = mlx5e_hv_vhca_stats_buf_max_size(priv); struct mlx5_hv_vhca_agent *agent; priv->stats_agent.buf = kvzalloc(buf_len, GFP_KERNEL); @@ -155,5 +161,7 @@ void mlx5e_hv_vhca_stats_destroy(struct mlx5e_priv *priv) return; mlx5_hv_vhca_agent_destroy(priv->stats_agent.agent); + priv->stats_agent.agent = NULL; kvfree(priv->stats_agent.buf); + priv->stats_agent.buf = NULL; }