rsi_get_* functions rely on an offset variable from usb
input. The size of usb input is RSI_MAX_RX_USB_PKT_SIZE(3000),
while 2-byte offset can be up to 0xFFFF. Thus a large offset
can cause out-of-bounds read.
The patch adds a bound checking condition when rcv_pkt_len is 0,
indicating it's USB. It's unclear whether this is triggerable
from other type of bus. The following check might help in that case.
offset > rcv_pkt_len - FRAME_DESC_SZ
The bug is trigerrable with conpromised/malfunctioning USB devices.
I tested the patch with the crashing input and got no more bug report.
Attached is the KASAN report from fuzzing.
BUG: KASAN: slab-out-of-bounds in rsi_read_pkt+0x42e/0x500 [rsi_91x]
Read of size 2 at addr ffff888019439fdb by task RX-Thread/227
CPU: 0 PID: 227 Comm: RX-Thread Not tainted 5.6.0 #66
Call Trace:
dump_stack+0x76/0xa0
print_address_description.constprop.0+0x16/0x200
? rsi_read_pkt+0x42e/0x500 [rsi_91x]
? rsi_read_pkt+0x42e/0x500 [rsi_91x]
__kasan_report.cold+0x37/0x7c
? rsi_read_pkt+0x42e/0x500 [rsi_91x]
kasan_report+0xe/0x20
rsi_read_pkt+0x42e/0x500 [rsi_91x]
rsi_usb_rx_thread+0x1b1/0x2fc [rsi_usb]
? rsi_probe+0x16a0/0x16a0 [rsi_usb]
? _raw_spin_lock_irqsave+0x7b/0xd0
? _raw_spin_trylock_bh+0x120/0x120
? __wake_up_common+0x10b/0x520
? rsi_probe+0x16a0/0x16a0 [rsi_usb]
kthread+0x2b5/0x3b0
? kthread_create_on_node+0xd0/0xd0
ret_from_fork+0x22/0x40
Reported-by: Zekun Shen <bruceshenzk@xxxxxxxxx>
Reported-by: Brendan Dolan-Gavitt <brendandg@xxxxxxx>
Signed-off-by: Zekun Shen <bruceshenzk@xxxxxxxxx>
---
drivers/net/wireless/rsi/rsi_91x_main.c | 4 ++++
drivers/net/wireless/rsi/rsi_91x_usb.c | 1 -
drivers/net/wireless/rsi/rsi_usb.h | 2 ++
3 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/rsi/rsi_91x_main.c b/drivers/net/wireless/rsi/rsi_91x_main.c
index d98483298..61fc27714 100644
--- a/drivers/net/wireless/rsi/rsi_91x_main.c
+++ b/drivers/net/wireless/rsi/rsi_91x_main.c
@@ -23,6 +23,7 @@
#include "rsi_common.h"
#include "rsi_coex.h"
#include "rsi_hal.h"
+#include "rsi_usb.h"
u32 rsi_zone_enabled = /* INFO_ZONE |
INIT_ZONE |
@@ -168,6 +169,9 @@ int rsi_read_pkt(struct rsi_common *common, u8 *rx_pkt, s32 rcv_pkt_len)
frame_desc = &rx_pkt[index];
actual_length = *(u16 *)&frame_desc[0];
offset = *(u16 *)&frame_desc[2];
+ if (!rcv_pkt_len && offset >
+ RSI_MAX_RX_USB_PKT_SIZE - FRAME_DESC_SZ)
+ goto fail;
queueno = rsi_get_queueno(frame_desc, offset);
length = rsi_get_length(frame_desc, offset);
diff --git a/drivers/net/wireless/rsi/rsi_91x_usb.c b/drivers/net/wireless/rsi/rsi_91x_usb.c
index d9e9bf26e..49ae4ae69 100644
--- a/drivers/net/wireless/rsi/rsi_91x_usb.c
+++ b/drivers/net/wireless/rsi/rsi_91x_usb.c
@@ -333,7 +333,6 @@ static int rsi_rx_urb_submit(struct rsi_hw *adapter, u8 ep_num, gfp_t mem_flags)
struct sk_buff *skb;
u8 dword_align_bytes = 0;
-#define RSI_MAX_RX_USB_PKT_SIZE 3000
skb = dev_alloc_skb(RSI_MAX_RX_USB_PKT_SIZE);
if (!skb)
return -ENOMEM;
diff --git a/drivers/net/wireless/rsi/rsi_usb.h b/drivers/net/wireless/rsi/rsi_usb.h
index 254d19b66..961851748 100644
--- a/drivers/net/wireless/rsi/rsi_usb.h
+++ b/drivers/net/wireless/rsi/rsi_usb.h
@@ -44,6 +44,8 @@
#define RSI_USB_BUF_SIZE 4096
#define RSI_USB_CTRL_BUF_SIZE 0x04
+#define RSI_MAX_RX_USB_PKT_SIZE 3000
+
struct rx_usb_ctrl_block {
u8 *data;
struct urb *rx_urb;
--
2.25.1
