[PATCH] staging: rtl8723bs: wifi_regd.c: Fix incorrect number of regulatory rules

[Chen-Yu Tsai]

From: Chen-Yu Tsai <wens at csie.org>

The custom regulatory ruleset in the rtl8723bs driver lists an incorrect
number of rules: one too many. This results in an out-of-bounds access,
as detected by KASAN. This was possible thanks to the newly added support
for KASAN on ARMv7.

Fix this by filling in the correct number of rules given.

KASAN report:

==================================================================
BUG: KASAN: global-out-of-bounds in cfg80211_does_bw_fit_range+0x14/0x4c [cfg80211]
Read of size 4 at addr bf20c254 by task ip/971

CPU: 2 PID: 971 Comm: ip Tainted: G         C        5.11.0-rc2-00020-gf7fe528a7ebe #1
Hardware name: Allwinner sun8i Family
[<c0113338>] (unwind_backtrace) from [<c010e8a4>] (show_stack+0x10/0x14)
[<c010e8a4>] (show_stack) from [<c0e0f868>] (dump_stack+0x9c/0xb4)
[<c0e0f868>] (dump_stack) from [<c0388284>] (print_address_description.constprop.2+0x1dc/0x2dc)
[<c0388284>] (print_address_description.constprop.2) from [<c03885cc>] (kasan_report+0x1a8/0x1c4)
[<c03885cc>] (kasan_report) from [<bf00a354>] (cfg80211_does_bw_fit_range+0x14/0x4c [cfg80211])
[<bf00a354>] (cfg80211_does_bw_fit_range [cfg80211]) from [<bf00b41c>] (freq_reg_info_regd.part.6+0x108/0x124 [>
[<bf00b41c>] (freq_reg_info_regd.part.6 [cfg80211]) from [<bf00df00>] (handle_channel_custom.constprop.12+0x48/>
[<bf00df00>] (handle_channel_custom.constprop.12 [cfg80211]) from [<bf00e150>] (wiphy_apply_custom_regulatory+0>
[<bf00e150>] (wiphy_apply_custom_regulatory [cfg80211]) from [<bf1fb9e8>] (rtw_regd_init+0x60/0x70 [r8723bs])
[<bf1fb9e8>] (rtw_regd_init [r8723bs]) from [<bf1ee5a8>] (rtw_cfg80211_init_wiphy+0x164/0x1e8 [r8723bs])
[<bf1ee5a8>] (rtw_cfg80211_init_wiphy [r8723bs]) from [<bf1f8d50>] (_netdev_open+0xe4/0x28c [r8723bs])
[<bf1f8d50>] (_netdev_open [r8723bs]) from [<bf1f8f58>] (netdev_open+0x60/0x88 [r8723bs])
[<bf1f8f58>] (netdev_open [r8723bs]) from [<c0bb3730>] (__dev_open+0x178/0x220)
[<c0bb3730>] (__dev_open) from [<c0bb3cdc>] (__dev_change_flags+0x258/0x2c4)
[<c0bb3cdc>] (__dev_change_flags) from [<c0bb3d88>] (dev_change_flags+0x40/0x80)
[<c0bb3d88>] (dev_change_flags) from [<c0bc86fc>] (do_setlink+0x538/0x1160)
[<c0bc86fc>] (do_setlink) from [<c0bcf9e8>] (__rtnl_newlink+0x65c/0xad8)
[<c0bcf9e8>] (__rtnl_newlink) from [<c0bcfeb0>] (rtnl_newlink+0x4c/0x6c)
[<c0bcfeb0>] (rtnl_newlink) from [<c0bc67c8>] (rtnetlink_rcv_msg+0x1f8/0x454)
[<c0bc67c8>] (rtnetlink_rcv_msg) from [<c0c330e4>] (netlink_rcv_skb+0xc4/0x1e0)
[<c0c330e4>] (netlink_rcv_skb) from [<c0c32478>] (netlink_unicast+0x2c8/0x3c4)
[<c0c32478>] (netlink_unicast) from [<c0c32894>] (netlink_sendmsg+0x320/0x5f0)
[<c0c32894>] (netlink_sendmsg) from [<c0b75eb0>] (____sys_sendmsg+0x320/0x3e0)
[<c0b75eb0>] (____sys_sendmsg) from [<c0b78394>] (___sys_sendmsg+0xe8/0x12c)
[<c0b78394>] (___sys_sendmsg) from [<c0b78a50>] (__sys_sendmsg+0xc0/0x120)
[<c0b78a50>] (__sys_sendmsg) from [<c0100060>] (ret_fast_syscall+0x0/0x58)
Exception stack(0xc5693fa8 to 0xc5693ff0)
3fa0:                   00000074 c7a39800 00000003 b6cee648 00000000 00000000
3fc0: 00000074 c7a39800 00000001 00000128 78d18349 00000000 b6ceeda0 004f7cb0
3fe0: 00000128 b6cee5e8 aeca151f aec1d746

The buggy address belongs to the variable:
 rtw_drv_halt+0xf908/0x6b4 [r8723bs]

Memory state around the buggy address:
 bf20c100: 00 00 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9
 bf20c180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>bf20c200: 00 00 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9
                                         ^
 bf20c280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 bf20c300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Chen-Yu Tsai <wens at csie.org>
---
 drivers/staging/rtl8723bs/os_dep/wifi_regd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/os_dep/wifi_regd.c b/drivers/staging/rtl8723bs/os_dep/wifi_regd.c
index 578b9f734231..65592bf84f38 100644
--- a/drivers/staging/rtl8723bs/os_dep/wifi_regd.c
+++ b/drivers/staging/rtl8723bs/os_dep/wifi_regd.c
@@ -34,7 +34,7 @@
 	NL80211_RRF_PASSIVE_SCAN)
 
 static const struct ieee80211_regdomain rtw_regdom_rd = {
-	.n_reg_rules = 3,
+	.n_reg_rules = 2,
 	.alpha2 = "99",
 	.reg_rules = {
 		RTW_2GHZ_CH01_11,
-- 
2.29.2