[PATCH net] ice: fix stats array overflow when VF requests more queues

[Michal Schmidt <mschmidt@redhat.com>]

When a VF increases its queue count via VIRTCHNL_OP_REQUEST_QUEUES,
ice_vc_request_qs_msg() sets vf->num_req_qs and triggers a VF reset.
The reset calls ice_vf_reconfig_vsi(), which does ice_vsi_decfg()
followed by ice_vsi_cfg(). ice_vsi_decfg() does not free the per-ring
stats arrays. Inside ice_vsi_cfg_def(), ice_vsi_set_num_qs() updates
alloc_txq/alloc_rxq to the new larger value, but
ice_vsi_alloc_stat_arrays() returns early because the stats already
exist. ice_vsi_alloc_ring_stats() then iterates using the new larger
alloc_txq and writes beyond the bounds of the old, smaller
tx_ring_stats/rx_ring_stats pointer arrays, corrupting adjacent SLUB
metadata.

KASAN detects the bug:
 ==================================================================
 BUG: KASAN: slab-out-of-bounds in ice_vsi_alloc_ring_stats+0x385/0x4a0 [ice]
 Read of size 8 at addr ffff88810affea60 by task kworker/u131:7/221

 CPU: 24 UID: 0 PID: 221 Comm: kworker/u131:7 Not tainted 7.1.0-rc1+ #1 PREEMPT(lazy)
 ...
 Workqueue: ice ice_service_task [ice]
 Call Trace:
  <TASK>
  ...
  kasan_report+0xd7/0x120
  ice_vsi_alloc_ring_stats+0x385/0x4a0 [ice]
  ice_vsi_cfg_def+0x12e2/0x2060 [ice]
  ice_vsi_cfg+0xb5/0x3c0 [ice]
  ice_reset_vf+0x858/0xf80 [ice]
  ice_vc_request_qs_msg+0x1da/0x290 [ice]
  ice_vc_process_vf_msg+0xb15/0x1430 [ice]
  __ice_clean_ctrlq+0x70d/0x9d0 [ice]
  ice_service_task+0x840/0xf20 [ice]
  process_one_work+0x690/0xff0
  worker_thread+0x4d9/0xd20
  kthread+0x322/0x410
  ret_from_fork+0x332/0x660
  ret_from_fork_asm+0x1a/0x30
  </TASK>

 Allocated by task 2439:
  kasan_save_stack+0x1c/0x40
  kasan_save_track+0x10/0x30
  __kasan_kmalloc+0x96/0xb0
  __kmalloc_noprof+0x1d8/0x580
  ice_vsi_cfg_def+0x115c/0x2060 [ice]
  ice_vsi_cfg+0xb5/0x3c0 [ice]
  ice_vsi_setup+0x180/0x320 [ice]
  ice_start_vfs+0x1f3/0x590 [ice]
  ice_ena_vfs+0x66d/0x798 [ice]
  ice_sriov_configure.cold+0xe4/0x121 [ice]
  sriov_numvfs_store+0x279/0x480
  kernfs_fop_write_iter+0x331/0x4f0
  vfs_write+0x4c4/0xe40
  ksys_write+0x10c/0x240
  do_syscall_64+0xd9/0x650
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

 The buggy address belongs to the object at ffff88810affea40
                which belongs to the cache kmalloc-32 of size 32
 The buggy address is located 0 bytes to the right of
                allocated 32-byte region [ffff88810affea40, ffff88810affea60)
 ...
 ==================================================================

ice_vsi_rebuild() handles this correctly by calling
ice_vsi_realloc_stat_arrays() before reconfiguration, but
ice_vf_reconfig_vsi() was missing this call.

Fix by calling ice_vsi_realloc_stat_arrays() in ice_vf_reconfig_vsi()
before ice_vsi_decfg(), mirroring the ice_vsi_rebuild() pattern. Set
vsi->req_txq/req_rxq from vf->num_req_qs so the realloc function knows
the target array size.

See the linked RHEL Jira item for a reproducer.

Fixes: 2a2cb4c6c181 ("ice: replace ice_vf_recreate_vsi() with ice_vf_reconfig_vsi()")
Closes: https://redhat.atlassian.net/browse/RHEL-164321
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Assisted-by: Claude:claude-opus-4-6 semcode
---
 drivers/net/ethernet/intel/ice/ice_lib.c    | 2 +-
 drivers/net/ethernet/intel/ice/ice_lib.h    | 1 +
 drivers/net/ethernet/intel/ice/ice_vf_lib.c | 7 +++++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index 837b71b7b2b7..fc78176a2a8d 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -3015,7 +3015,7 @@ ice_vsi_rebuild_set_coalesce(struct ice_vsi *vsi,
  * ice_vsi_realloc_stat_arrays - Frees unused stat structures or alloc new ones
  * @vsi: VSI pointer
  */
-static int
+int
 ice_vsi_realloc_stat_arrays(struct ice_vsi *vsi)
 {
 	u16 req_txq = vsi->req_txq ? vsi->req_txq : vsi->alloc_txq;
diff --git a/drivers/net/ethernet/intel/ice/ice_lib.h b/drivers/net/ethernet/intel/ice/ice_lib.h
index 49454d98dcfe..6f7da84384e5 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.h
+++ b/drivers/net/ethernet/intel/ice/ice_lib.h
@@ -66,6 +66,7 @@ int ice_ena_vsi(struct ice_vsi *vsi, bool locked);
 void ice_vsi_decfg(struct ice_vsi *vsi);
 void ice_dis_vsi(struct ice_vsi *vsi, bool locked);
 
+int ice_vsi_realloc_stat_arrays(struct ice_vsi *vsi);
 int ice_vsi_rebuild(struct ice_vsi *vsi, u32 vsi_flags);
 int ice_vsi_cfg(struct ice_vsi *vsi);
 struct ice_vsi *ice_vsi_alloc(struct ice_pf *pf);
diff --git a/drivers/net/ethernet/intel/ice/ice_vf_lib.c b/drivers/net/ethernet/intel/ice/ice_vf_lib.c
index 772f6b07340d..9edb2c14f553 100644
--- a/drivers/net/ethernet/intel/ice/ice_vf_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_vf_lib.c
@@ -268,6 +268,13 @@ static int ice_vf_reconfig_vsi(struct ice_vf *vf)
 
 	vsi->flags = ICE_VSI_FLAG_NO_INIT;
 
+	vsi->req_txq = vf->num_req_qs;
+	vsi->req_rxq = vf->num_req_qs;
+
+	err = ice_vsi_realloc_stat_arrays(vsi);
+	if (err)
+		return err;
+
 	ice_vsi_decfg(vsi);
 	ice_fltr_remove_all(vsi);
 
-- 
2.54.0