bnxt_en: Fix possible crash after creating sw mqprio TCs

The driver relies on netdev_get_num_tc() to get the number of HW
offloaded mqprio TCs to allocate and free TX rings.  This won't
work and can potentially crash the system if software mqprio or
taprio TCs have been setup.  netdev_get_num_tc() will return the
number of software TCs and it may cause the driver to allocate or
free more TX rings that it should.  Fix it by adding a bp->num_tc
field to store the number of HW offload mqprio TCs for the device.
Use bp->num_tc instead of netdev_get_num_tc().

This fixes a crash like this:

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 42b8404067 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 120 PID: 8661 Comm: ifconfig Kdump: loaded Tainted: G           OE     5.18.16 #1
Hardware name: Lenovo ThinkSystem SR650 V3/SB27A92818, BIOS ESE114N-2.12 04/25/2023
RIP: 0010:bnxt_hwrm_cp_ring_alloc_p5+0x10/0x90 [bnxt_en]
Code: 41 5c 41 5d 41 5e c3 cc cc cc cc 41 8b 44 24 08 66 89 03 eb c6 e8 b0 f1 7d db 0f 1f 44 00 00 41 56 41 55 41 54 55 48 89 fd 53 <48> 8b 06 48 89 f3 48 81 c6 28 01 00 00 0f b6 96 13 ff ff ff 44 8b
RSP: 0018:ff65907660d1fa88 EFLAGS: 00010202
RAX: 0000000000000010 RBX: ff4dde1d907e4980 RCX: f400000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ff4dde1d907e4980
RBP: ff4dde1d907e4980 R08: 000000000000000f R09: 0000000000000000
R10: ff4dde5f02671800 R11: 0000000000000008 R12: 0000000088888889
R13: 0500000000000000 R14: 00f0000000000000 R15: ff4dde5f02671800
FS:  00007f4b126b5740(0000) GS:ff4dde9bff600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000416f9c6002 CR4: 0000000000771ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 bnxt_hwrm_ring_alloc+0x204/0x770 [bnxt_en]
 bnxt_init_chip+0x4d/0x680 [bnxt_en]
 ? bnxt_poll+0x1a0/0x1a0 [bnxt_en]
 __bnxt_open_nic+0xd2/0x740 [bnxt_en]
 bnxt_open+0x10b/0x220 [bnxt_en]
 ? raw_notifier_call_chain+0x41/0x60
 __dev_open+0xf3/0x1b0
 __dev_change_flags+0x1db/0x250
 dev_change_flags+0x21/0x60
 devinet_ioctl+0x590/0x720
 ? avc_has_extended_perms+0x1b7/0x420
 ? _copy_from_user+0x3a/0x60
 inet_ioctl+0x189/0x1c0
 ? wp_page_copy+0x45a/0x6e0
 sock_do_ioctl+0x42/0xf0
 ? ioctl_has_perm.constprop.0.isra.0+0xbd/0x120
 sock_ioctl+0x1ce/0x2e0
 __x64_sys_ioctl+0x87/0xc0
 do_syscall_64+0x59/0x90
 ? syscall_exit_work+0x103/0x130
 ? syscall_exit_to_user_mode+0x12/0x30
 ? do_syscall_64+0x69/0x90
 ? exc_page_fault+0x62/0x150

Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.")
Reviewed-by: Damodharam Ammepalli <damodharam.ammepalli@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://lore.kernel.org/r/20240117234515.226944-6-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 1f6e0cd84f2e..dc4ca706b0e2 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -884,7 +884,7 @@ static void bnxt_get_channels(struct net_device *dev,
 	if (max_tx_sch_inputs)
 		max_tx_rings = min_t(int, max_tx_rings, max_tx_sch_inputs);
 
-	tcs = netdev_get_num_tc(dev);
+	tcs = bp->num_tc;
 	tx_grps = max(tcs, 1);
 	if (bp->tx_nr_rings_xdp)
 		tx_grps++;
@@ -944,7 +944,7 @@ static int bnxt_set_channels(struct net_device *dev,
 	if (channel->combined_count)
 		sh = true;
 
-	tcs = netdev_get_num_tc(dev);
+	tcs = bp->num_tc;
 
 	req_tx_rings = sh ? channel->combined_count : channel->tx_count;
 	req_rx_rings = sh ? channel->combined_count : channel->rx_count;