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Subject[PATCH 5.4 172/320] rsi: Fix out-of-bounds read in rsi_read_pkt()
Date
From: Zekun Shen <bruceshenzk@gmail.com>

[ 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>
---
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 441fda71f6289..d92337169ee3a 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 |
@@ -167,6 +168,9 @@ 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 730d7bf86c40c..94bf2a7ca635d 100644
--- a/drivers/net/wireless/rsi/rsi_91x_usb.c
+++ b/drivers/net/wireless/rsi/rsi_91x_usb.c
@@ -320,7 +320,6 @@ 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 8702f434b5699..ad88f8c70a351 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;
--
2.34.1


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