eth: bnxt: fix kernel panic in the bnxt_get_queue_stats{rx | tx}

JIRA: https://issues.redhat.com/browse/RHEL-106550
CVE: CVE-2025-21973

commit f09af5f
Author: Taehee Yoo <[email protected]>
Date:   Sun Mar 9 13:42:16 2025 +0000

    eth: bnxt: fix kernel panic in the bnxt_get_queue_stats{rx | tx}

    When qstats-get operation is executed, callbacks of netdev_stats_ops
    are called. The bnxt_get_queue_stats{rx | tx} collect per-queue stats
    from sw_stats in the rings.
    But {rx | tx | cp}_ring are allocated when the interface is up.
    So, these rings are not allocated when the interface is down.

    The qstats-get is allowed even if the interface is down. However,
    the bnxt_get_queue_stats{rx | tx}() accesses cp_ring and tx_ring
    without null check.
    So, it needs to avoid accessing rings if the interface is down.

    Reproducer:
     ip link set $interface down
     ./cli.py --spec netdev.yaml --dump qstats-get
    OR
     ip link set $interface down
     python ./stats.py

    Splat looks like:
     BUG: kernel NULL pointer dereference, address: 0000000000000000
     #PF: supervisor read access in kernel mode
     #PF: error_code(0x0000) - not-present page
     PGD 1680fa067 P4D 1680fa067 PUD 16be3b067 PMD 0
     Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
     CPU: 0 UID: 0 PID: 1495 Comm: python3 Not tainted 6.14.0-rc4+ #32 5cd0f999d5a15c574ac72b3e4b907341
     Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021
     RIP: 0010:bnxt_get_queue_stats_rx+0xf/0x70 [bnxt_en]
     Code: c6 87 b5 18 00 00 02 eb a2 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 01
     RSP: 0018:ffffabef43cdb7e0 EFLAGS: 00010282
     RAX: 0000000000000000 RBX: ffffffffc04c8710 RCX: 0000000000000000
     RDX: ffffabef43cdb858 RSI: 0000000000000000 RDI: ffff8d504e850000
     RBP: ffff8d506c9f9c00 R08: 0000000000000004 R09: ffff8d506bcd901c
     R10: 0000000000000015 R11: ffff8d506bcd9000 R12: 0000000000000000
     R13: ffffabef43cdb8c0 R14: ffff8d504e850000 R15: 0000000000000000
     FS:  00007f2c5462b080(0000) GS:ffff8d575f600000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: 0000000000000000 CR3: 0000000167fd0000 CR4: 00000000007506f0
     PKRU: 55555554
     Call Trace:
      <TASK>
      ? __die+0x20/0x70
      ? page_fault_oops+0x15a/0x460
      ? sched_balance_find_src_group+0x58d/0xd10
      ? exc_page_fault+0x6e/0x180
      ? asm_exc_page_fault+0x22/0x30
      ? bnxt_get_queue_stats_rx+0xf/0x70 [bnxt_en cdd546fd48563c280cfd30e9647efa420db07bf1]
      netdev_nl_stats_by_netdev+0x2b1/0x4e0
      ? xas_load+0x9/0xb0
      ? xas_find+0x183/0x1d0
      ? xa_find+0x8b/0xe0
      netdev_nl_qstats_get_dumpit+0xbf/0x1e0
      genl_dumpit+0x31/0x90
      netlink_dump+0x1a8/0x360

    Fixes: af7b3b4 ("eth: bnxt: support per-queue statistics")
    Signed-off-by: Taehee Yoo <[email protected]>
    Reviewed-by: Somnath Kotur <[email protected]>
    Link: https://patch.msgid.link/[email protected]
    Signed-off-by: Jakub Kicinski <[email protected]>

Signed-off-by: Michal Schmidt <[email protected]>

Author: michich

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -15518,6 +15518,9 @@ static void bnxt_get_queue_stats_rx(struct net_device *dev, int i,
 	struct bnxt_cp_ring_info *cpr;
 	u64 *sw;
 
+	if (!bp->bnapi)
+		return;
+
 	cpr = &bp->bnapi[i]->cp_ring;
 	sw = cpr->stats.sw_stats;
 
@@ -15541,6 +15544,9 @@ static void bnxt_get_queue_stats_tx(struct net_device *dev, int i,
 	struct bnxt_napi *bnapi;
 	u64 *sw;
 
+	if (!bp->tx_ring)
+		return;
+
 	bnapi = bp->tx_ring[bp->tx_ring_map[i]].bnapi;
 	sw = bnapi->cp_ring.stats.sw_stats;