[PATCH AUTOSEL 5.15 21/68] atlantic: fix double-free in aq_ring_tx_clean

Sasha Levin
2021-11-30T14:50:07Z

From: Zekun Shen <bruceshenzk@gmail.com>

[ Upstream commit 6a405f6c372d14707b87d3097b361b69899a26c8 ]

We found this bug while fuzzing the device driver. Using and freeing
the dangling pointer buff->skb would cause use-after-free and
double-free.

This bug is triggerable with compromised/malfunctioning devices. We
found the bug with QEMU emulation and tested the patch by emulation.
We did NOT test on a real device.

Attached is the bug report.

BUG: KASAN: double-free or invalid-free in consume_skb+0x6c/0x1c0

Call Trace:
dump_stack+0x76/0xa0
print_address_description.constprop.0+0x16/0x200
? consume_skb+0x6c/0x1c0
kasan_report_invalid_free+0x61/0xa0
? consume_skb+0x6c/0x1c0
__kasan_slab_free+0x15e/0x170
? consume_skb+0x6c/0x1c0
kfree+0x8c/0x230
consume_skb+0x6c/0x1c0
aq_ring_tx_clean+0x5c2/0xa80 [atlantic]
aq_vec_poll+0x309/0x5d0 [atlantic]
? _sub_I_65535_1+0x20/0x20 [atlantic]
? __next_timer_interrupt+0xba/0xf0
net_rx_action+0x363/0xbd0
? call_timer_fn+0x240/0x240
? __switch_to_asm+0x34/0x70
? napi_busy_loop+0x520/0x520
? net_tx_action+0x379/0x720
__do_softirq+0x18c/0x634
? takeover_tasklets+0x5f0/0x5f0
run_ksoftirqd+0x15/0x20
smpboot_thread_fn+0x2f1/0x6b0
? smpboot_unregister_percpu_thread+0x160/0x160
? __kthread_parkme+0x80/0x100
? smpboot_unregister_percpu_thread+0x160/0x160
kthread+0x2b5/0x3b0
? kthread_create_on_node+0xd0/0xd0
ret_from_fork+0x22/0x40

Reported-by: Brendan Dolan-Gavitt <brendandg@nyu.edu>
Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
Reviewed-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 24122ccda614c..81b3756417ec2 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -298,13 +298,14 @@ bool aq_ring_tx_clean(struct aq_ring_s *self)
}
}

- if (unlikely(buff->is_eop)) {
+ if (unlikely(buff->is_eop && buff->skb)) {
u64_stats_update_begin(&self->stats.tx.syncp);
++self->stats.tx.packets;
self->stats.tx.bytes += buff->skb->len;
u64_stats_update_end(&self->stats.tx.syncp);

dev_kfree_skb_any(buff->skb);
+ buff->skb = NULL;
}
buff->pa = 0U;
buff->eop_index = 0xffffU;
--
2.33.0