4.19-stable review patch. If anyone has any objections, please let me know.
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From: Su Hui suhui@nfschina.com
[ Upstream commit bc8263083af60e7e57c6120edbc1f75d6c909a35 ]
Clang static checker warns:
drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c:184:49: The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'u32'. [core.UndefinedBinaryOperatorResult]
If the value of the right operand is negative or is greater than or equal to the width of the promoted left operand, the behavior is undefined.[1][2]
For example, when using different gcc's compilation optimization options (-O0 or -O2), the result of '(u32)data << 32' is different. One is 0, the other is old value of data. Let _rtl8821ae_phy_calculate_bit_shift()'s return value less than 32 to fix this problem. Warn if bitmask is zero.
[1] https://stackoverflow.com/questions/11270492/what-does-the-c-standard-say-ab... [2] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf
Fixes: 21e4b0726dc6 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree") Signed-off-by: Su Hui suhui@nfschina.com Acked-by: Ping-Ke Shih pkshih@realtek.com Signed-off-by: Kalle Valo kvalo@kernel.org Link: https://lore.kernel.org/r/20231127013511.26694-2-suhui@nfschina.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c index 9ec62fff6f1a..a972afde40a7 100644 --- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c @@ -51,9 +51,10 @@ static void _rtl8821ae_phy_rf_serial_write(struct ieee80211_hw *hw, u32 data); static u32 _rtl8821ae_phy_calculate_bit_shift(u32 bitmask) { - u32 i = ffs(bitmask); + if (WARN_ON_ONCE(!bitmask)) + return 0;
- return i ? i - 1 : 32; + return __ffs(bitmask); } static bool _rtl8821ae_phy_bb8821a_config_parafile(struct ieee80211_hw *hw); /*static bool _rtl8812ae_phy_config_mac_with_headerfile(struct ieee80211_hw *hw);*/