[Cocci] [PATCH] staging: rtl8723bs: Fix two possible sleep-in-atomic-context bugs in translate_scan()

[Dan Carpenter]

The driver may sleep with holding a spinlock.
[FUNC] kzalloc(GFP_KERNEL)
kzalloc in translate_scan
translate_scan in rtw_wx_get_scan
spin_lock_bh in rtw_wx_get_scan
[FUNC] kzalloc(GFP_KERNEL)
kzalloc in translate_scan
translate_scan in rtw_wx_get_scan
spin_lock_bh in rtw_wx_get_scan
To fix these bugs, GFP_KERNEL is replaced with GFP_ATOMIC.
These bugs are found by my static analysis tool (DSAC-2) and checked by
my code review.
---
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
index b26533983864..7632b8974563 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -321,7 +321,7 @@ static char *translate_scan(struct adapter *padapter,
RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: ssid =%s\n", pnetwork->network.Ssid.Ssid));
RT_TRACE(_module_rtl871x_mlme_c_, _drv_info_, ("rtw_wx_get_scan: wpa_len =%d rsn_len =%d\n", wpa_len, rsn_len));
- buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_KERNEL);
+ buf = kzalloc(MAX_WPA_IE_LEN*2, GFP_ATOMIC);
if (!buf)
return start;

Thanks! It occurs to me that another way to detect this bug is that
one of the allocations in this function already uses GFP_ATOMIC. It
doesn't normally make sense to mix GFP_ATOMIC and GFP_KERNEL when there
isn't any locking in the function.

regards,
dan carpenter

[Dan Carpenter]

Post by Dan Carpenter
Thanks! It occurs to me that another way to detect this bug is that
one of the allocations in this function already uses GFP_ATOMIC. It
doesn't normally make sense to mix GFP_ATOMIC and GFP_KERNEL when there
isn't any locking in the function.

Yes, this pattern is interesting for bug finding :)
But to fix the bugs of this pattern, we need to decide whether GFP_ATOMIC or
GFP_KERNEL should be used here.

Sure. But either way it's a bug. Plus this would be the first static
checker warning which warns about using GFP_ATOMIC when it's supposed to
be GFP_KERNEL. #milestone

regards,
dan carpenter