Re: [PATCH v3 2/3] staging: rtl8712: fix uninit-value in r871xu_drv_init()

From: Pavel Skripkin
Date: Fri May 06 2022 - 08:29:39 EST

Hi Wang,

On 5/6/22 14:59, Wang Cheng wrote:
Reported-and-tested-by: syzbot+6f5ecd144854c0d8580b@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Wang Cheng <wanngchenng@xxxxxxxxx>
---
drivers/staging/rtl8712/usb_intf.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/rtl8712/usb_intf.c b/drivers/staging/rtl8712/usb_intf.c
index ee4c61f85a07..50dcd3ecb685 100644
--- a/drivers/staging/rtl8712/usb_intf.c
+++ b/drivers/staging/rtl8712/usb_intf.c
@@ -538,13 +538,13 @@ static int r871xu_drv_init(struct usb_interface *pusb_intf,
} else {
AutoloadFail = false;
}
- if (((mac[0] == 0xff) && (mac[1] == 0xff) &&
+ if ((!AutoloadFail) ||
+ ((mac[0] == 0xff) && (mac[1] == 0xff) &&
(mac[2] == 0xff) && (mac[3] == 0xff) &&
(mac[4] == 0xff) && (mac[5] == 0xff)) ||
((mac[0] == 0x00) && (mac[1] == 0x00) &&
(mac[2] == 0x00) && (mac[3] == 0x00) &&
- (mac[4] == 0x00) && (mac[5] == 0x00)) ||
- (!AutoloadFail)) {
+ (mac[4] == 0x00) && (mac[5] == 0x00))) {
mac[0] = 0x00;
mac[1] = 0xe0;
mac[2] = 0x4c;

Hmm,

the whole r871xu_drv_init() looks odd, but it's unrelated.

I see that this patch does not help with below kernel path

r871xu_drv_init()
if (tmpU1b & _EEPROM_EN) <- true [1]
if (!r8712_initmac || !mac_pton(r8712_initmac, mac)) <- (*)
if ((!AutoloadFail) || <- false, since [1] branch taken
[code touches stack data]

(*) false because of r8712_initmac is equal to NULL


I saw, that syzbot said OK on your patch, but it's because you have just hided an error inside read API



With regards,
Pavel Skripkin

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