rsi: Fix out-of-bounds read in rsi_read_pkt()

[ Upstream commit f1cb3476e48b60c450ec3a1d7da0805bffc6e43a ]

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: Brendan Dolan-Gavitt <brendandg@nyu.edu>
Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/YXxXS4wgu2OsmlVv@10-18-43-117.dynapool.wireless.nyu.edu
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/wireless/rsi/rsi_91x_main.c b/drivers/net/wireless/rsi/rsi_91x_main.c
index 8c638cf..fe8aed5 100644 (file)
--- 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 7f34148..11388a1 100644 (file)
--- a/drivers/net/wireless/rsi/rsi_91x_usb.c
+++ b/drivers/net/wireless/rsi/rsi_91x_usb.c
@@ -328,7 +328,6 @@ 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 8702f43..ad88f8c 100644 (file)
--- 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;