Subject: Re: [PATCH net 2/2] bonding: fix NULL deref in bond_rr_gen_slave_id

From: Jay Vosburgh <[email-masked]>
Date: Tue, 20 Sep 2022 05:59:06 -0700

Jonathan Toppins <[email-masked]> wrote:

>Fix a NULL dereference of the struct bonding.rr_tx_counter member because
>if a bond is initially created with an initial mode != zero (Round Robin)
>the memory required for the counter is never created and when the mode is
>changed there is never any attempt to verify the memory is allocated upon
>switching modes.
>
>This causes the following Oops on an aarch64 machine:
>    [  334.686773] Unable to handle kernel paging request at virtual address ffff2c91ac905000
>    [  334.694703] Mem abort info:
>    [  334.697486]   ESR = 0x0000000096000004
>    [  334.701234]   EC = 0x25: DABT (current EL), IL = 32 bits
>    [  334.706536]   SET = 0, FnV = 0
>    [  334.709579]   EA = 0, S1PTW = 0
>    [  334.712719]   FSC = 0x04: level 0 translation fault
>    [  334.717586] Data abort info:
>    [  334.720454]   ISV = 0, ISS = 0x00000004
>    [  334.724288]   CM = 0, WnR = 0
>    [  334.727244] swapper pgtable: 4k pages, 48-bit VAs, pgdp=000008044d662000
>    [  334.733944] [ffff2c91ac905000] pgd=0000000000000000, p4d=0000000000000000
>    [  334.740734] Internal error: Oops: 96000004 [#1] SMP
>    [  334.745602] Modules linked in: bonding tls veth rfkill sunrpc arm_spe_pmu vfat fat acpi_ipmi ipmi_ssif ixgbe igb i40e mdio ipmi_devintf ipmi_msghandler arm_cmn arm_dsu_pmu cppc_cpufreq acpi_tad fuse zram crct10dif_ce ast ghash_ce sbsa_gwdt nvme drm_vram_helper drm_ttm_helper nvme_core ttm xgene_hwmon
>    [  334.772217] CPU: 7 PID: 2214 Comm: ping Not tainted 6.0.0-rc4-00133-g64ae13ed4784 #4
>    [  334.779950] Hardware name: GIGABYTE R272-P31-00/MP32-AR1-00, BIOS F18v (SCP: 1.08.20211002) 12/01/2021
>    [  334.789244] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>    [  334.796196] pc : bond_rr_gen_slave_id+0x40/0x124 [bonding]
>    [  334.801691] lr : bond_xmit_roundrobin_slave_get+0x38/0xdc [bonding]
>    [  334.807962] sp : ffff8000221733e0
>    [  334.811265] x29: ffff8000221733e0 x28: ffffdbac8572d198 x27: ffff80002217357c
>    [  334.818392] x26: 000000000000002a x25: ffffdbacb33ee000 x24: ffff07ff980fa000
>    [  334.825519] x23: ffffdbacb2e398ba x22: ffff07ff98102000 x21: ffff07ff981029c0
>    [  334.832646] x20: 0000000000000001 x19: ffff07ff981029c0 x18: 0000000000000014
>    [  334.839773] x17: 0000000000000000 x16: ffffdbacb1004364 x15: 0000aaaabe2f5a62
>    [  334.846899] x14: ffff07ff8e55d968 x13: ffff07ff8e55db30 x12: 0000000000000000
>    [  334.854026] x11: ffffdbacb21532e8 x10: 0000000000000001 x9 : ffffdbac857178ec
>    [  334.861153] x8 : ffff07ff9f6e5a28 x7 : 0000000000000000 x6 : 000000007c2b3742
>    [  334.868279] x5 : ffff2c91ac905000 x4 : ffff2c91ac905000 x3 : ffff07ff9f554400
>    [  334.875406] x2 : ffff2c91ac905000 x1 : 0000000000000001 x0 : ffff07ff981029c0
>    [  334.882532] Call trace:
>    [  334.884967]  bond_rr_gen_slave_id+0x40/0x124 [bonding]
>    [  334.890109]  bond_xmit_roundrobin_slave_get+0x38/0xdc [bonding]
>    [  334.896033]  __bond_start_xmit+0x128/0x3a0 [bonding]
>    [  334.901001]  bond_start_xmit+0x54/0xb0 [bonding]
>    [  334.905622]  dev_hard_start_xmit+0xb4/0x220
>    [  334.909798]  __dev_queue_xmit+0x1a0/0x720
>    [  334.913799]  arp_xmit+0x3c/0xbc
>    [  334.916932]  arp_send_dst+0x98/0xd0
>    [  334.920410]  arp_solicit+0xe8/0x230
>    [  334.923888]  neigh_probe+0x60/0xb0
>    [  334.927279]  __neigh_event_send+0x3b0/0x470
>    [  334.931453]  neigh_resolve_output+0x70/0x90
>    [  334.935626]  ip_finish_output2+0x158/0x514
>    [  334.939714]  __ip_finish_output+0xac/0x1a4
>    [  334.943800]  ip_finish_output+0x40/0xfc
>    [  334.947626]  ip_output+0xf8/0x1a4
>    [  334.950931]  ip_send_skb+0x5c/0x100
>    [  334.954410]  ip_push_pending_frames+0x3c/0x60
>    [  334.958758]  raw_sendmsg+0x458/0x6d0
>    [  334.962325]  inet_sendmsg+0x50/0x80
>    [  334.965805]  sock_sendmsg+0x60/0x6c
>    [  334.969286]  __sys_sendto+0xc8/0x134
>    [  334.972853]  __arm64_sys_sendto+0x34/0x4c
>    [  334.976854]  invoke_syscall+0x78/0x100
>    [  334.980594]  el0_svc_common.constprop.0+0x4c/0xf4
>    [  334.985287]  do_el0_svc+0x38/0x4c
>    [  334.988591]  el0_svc+0x34/0x10c
>    [  334.991724]  el0t_64_sync_handler+0x11c/0x150
>    [  334.996072]  el0t_64_sync+0x190/0x194
>    [  334.999726] Code: b9001062 f9403c02 d53cd044 8b040042 (b8210040)
>    [  335.005810] ---[ end trace 0000000000000000 ]---
>    [  335.010416] Kernel panic - not syncing: Oops: Fatal exception in interrupt
>    [  335.017279] SMP: stopping secondary CPUs
>    [  335.021374] Kernel Offset: 0x5baca8eb0000 from 0xffff800008000000
>    [  335.027456] PHYS_OFFSET: 0x80000000
>    [  335.030932] CPU features: 0x0000,0085c029,19805c82
>    [  335.035713] Memory Limit: none
>    [  335.038756] Rebooting in 180 seconds..
>
>The is to allocate the memory in bond_open() which is guaranteed to be
    ^
   "fix" or "remedy" or the like here?

	Other than the missing word, the patch looks good to me.

	-J

>called before any packets are processed.
>
>Fixes: 848ca9182a7d ("net: bonding: Use per-cpu rr_tx_counter")
>Signed-off-by: Jonathan Toppins <[email-masked]>
>---
> drivers/net/bonding/bond_main.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index bc6d8b0aa6fb..86d42306aa5e 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -4182,6 +4182,12 @@ static int bond_open(struct net_device *bond_dev)
> 	struct list_head *iter;
> 	struct slave *slave;
> 
>+	if (BOND_MODE(bond) == BOND_MODE_ROUNDROBIN && !bond->rr_tx_counter) {
>+		bond->rr_tx_counter = alloc_percpu(u32);
>+		if (!bond->rr_tx_counter)
>+			return -ENOMEM;
>+	}
>+
> 	/* reset slave->backup and slave->inactive */
> 	if (bond_has_slaves(bond)) {
> 		bond_for_each_slave(bond, slave, iter) {
>@@ -6243,15 +6249,6 @@ static int bond_init(struct net_device *bond_dev)
> 	if (!bond->wq)
> 		return -ENOMEM;
> 
>-	if (BOND_MODE(bond) == BOND_MODE_ROUNDROBIN) {
>-		bond->rr_tx_counter = alloc_percpu(u32);
>-		if (!bond->rr_tx_counter) {
>-			destroy_workqueue(bond->wq);
>-			bond->wq = NULL;
>-			return -ENOMEM;
>-		}
>-	}
>-
> 	spin_lock_init(&bond->stats_lock);
> 	netdev_lockdep_set_classes(bond_dev);
> 
>-- 
>2.31.1
>

---
	-Jay Vosburgh, [email-masked]