From: Zekun Shen bruceshenzk@gmail.com
[ Upstream commit 0f296e782f21dc1c55475a3c107ac68ab09cc1cf ]
This bug report came up when we were testing the device driver by fuzzing. It shows that buf1_len can get underflowed and be 0xfffffffc (4294967292).
This bug is triggerable with a compromised/malfunctioning device. We found the bug through QEMU emulation tested the patch with emulation. We did NOT test it on real hardware.
Attached is the bug report by fuzzing.
BUG: KASAN: use-after-free in stmmac_napi_poll_rx+0x1c08/0x36e0 [stmmac] Read of size 4294967292 at addr ffff888016358000 by task ksoftirqd/0/9
CPU: 0 PID: 9 Comm: ksoftirqd/0 Tainted: G W 5.6.0 #1 Call Trace: dump_stack+0x76/0xa0 print_address_description.constprop.0+0x16/0x200 ? stmmac_napi_poll_rx+0x1c08/0x36e0 [stmmac] ? stmmac_napi_poll_rx+0x1c08/0x36e0 [stmmac] __kasan_report.cold+0x37/0x7c ? stmmac_napi_poll_rx+0x1c08/0x36e0 [stmmac] kasan_report+0xe/0x20 check_memory_region+0x15a/0x1d0 memcpy+0x20/0x50 stmmac_napi_poll_rx+0x1c08/0x36e0 [stmmac] ? stmmac_suspend+0x850/0x850 [stmmac] ? __next_timer_interrupt+0xba/0xf0 net_rx_action+0x363/0xbd0 ? call_timer_fn+0x240/0x240 ? __switch_to_asm+0x40/0x70 ? napi_busy_loop+0x520/0x520 ? __schedule+0x839/0x15a0 __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 Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 4a75e73f06bbd..197029b4c11a1 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -3873,12 +3873,13 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) if (likely(!(status & rx_not_ls)) && (likely(priv->synopsys_id >= DWMAC_CORE_4_00) || unlikely(status != llc_snap))) { - if (buf2_len) + if (buf2_len) { buf2_len -= ETH_FCS_LEN; - else + len -= ETH_FCS_LEN; + } else if (buf1_len) { buf1_len -= ETH_FCS_LEN; - - len -= ETH_FCS_LEN; + len -= ETH_FCS_LEN; + } }
if (!skb) {