staging/rtl8192u: Prefer kcalloc over open coded arithmetic
v2 cover staging/rtl8192u: Prefer kcalloc over open coded arithmetic
The main reason of this patch serie is to avoid size calculations (especially multiplication) in memory allocator function arguments due to the risk of them overflowing [1]. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors.
At the same time, take the opportunity to refactor the function avoiding CamelCase in the name of variables and moving some initializations to the variables definition block.
Changelog v1 -> v2
- Split the CamelCase refactoring and the moving of initializations in two separate commits (Kees Cook).
- Link to the documentation to clarify the change in the 3/3 patch (Kees Cook).
- Modify the commit message to clarify in the 3/3 patch that these changes are not dynamic sizes but it is best to do the change to keep the open-coded math idiom out of code (Kees Cook).
Len Baker (3):
staging/rtl8192u: Avoid CamelCase in names of variables staging/rtl8192u: Initialize variables in the definition block staging/rtl8192u: Prefer kcalloc over open coded arithmetic
drivers/staging/rtl8192u/r819xU_phy.c | 92 +++++++++++++-------------- 1 file changed, 44 insertions(+), 48 deletions(-)
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2.25.1
PATCH v2 1/3 staging/rtl8192u: Avoid CamelCase in names of variables
Avoid CameCase in the names of all local variables inside the function rtl8192_phy_SwChnlStepByStep().
--- drivers/staging/rtl8192u/r819xU_phy.c | 95 +++++++++++++-------------- 1 file changed, 47 insertions(+), 48 deletions(-)
drivers/staging/rtl8192u/r819xU_phy.c +47 -48
@@ -1185,30 +1185,30 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, u8 *stage, u8 *step, u32 *delay) {struct r8192_priv *priv =ieee80211_priv (dev); -struct sw_chnl_cmd *PreCommonCmd; -u32 PreCommonCmdCnt; -struct sw_chnl_cmd *PostCommonCmd; -u32 PostCommonCmdCnt; -struct sw_chnl_cmd *RfDependCmd; -u32 RfDependCmdCnt; -struct sw_chnl_cmd *CurrentCmd =NULL ; -u8 e_rfpath; -bool ret; - - PreCommonCmd =kzalloc (sizeof (*PreCommonCmd) *MAX_PRECMD_CNT ,GFP_KERNEL ); -if (!PreCommonCmd) +struct sw_chnl_cmd *pre_cmd; +u32 pre_cmd_cnt; +struct sw_chnl_cmd *post_cmd; +u32 post_cmd_cnt; +struct sw_chnl_cmd *rf_cmd; +u32 rf_cmd_cnt; +struct sw_chnl_cmd *current_cmd =NULL ; +u8 e_rfpath; +bool ret; + + pre_cmd =kzalloc (sizeof (*pre_cmd) *MAX_PRECMD_CNT ,GFP_KERNEL ); +if (!pre_cmd)return false; - PostCommonCmd =kzalloc (sizeof (*PostCommonCmd) *MAX_POSTCMD_CNT ,GFP_KERNEL ); -if (!PostCommonCmd) { -kfree (PreCommonCmd); + post_cmd =kzalloc (sizeof (*post_cmd) *MAX_POSTCMD_CNT ,GFP_KERNEL ); +if (!post_cmd) { +kfree (pre_cmd);return false; } - RfDependCmd =kzalloc (sizeof (*RfDependCmd) *MAX_RFDEPENDCMD_CNT ,GFP_KERNEL ); -if (!RfDependCmd) { -kfree (PreCommonCmd); -kfree (PostCommonCmd); + rf_cmd =kzalloc (sizeof (*rf_cmd) *MAX_RFDEPENDCMD_CNT ,GFP_KERNEL ); +if (!rf_cmd) { +kfree (pre_cmd); +kfree (post_cmd);return false; }
@@ -1225,21 +1225,20 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,/* FIXME: need to check whether channel is legal or not here */ /* <1> Fill up pre common command. */ - PreCommonCmdCnt =0 ; -rtl8192_phy_SetSwChnlCmdArray (PreCommonCmd, PreCommonCmdCnt++, + pre_cmd_cnt =0 ; +rtl8192_phy_SetSwChnlCmdArray (pre_cmd, pre_cmd_cnt++,MAX_PRECMD_CNT ,CMD_ID_SET_TX_PWR_LEVEL ,0 ,0 ,0 ); -rtl8192_phy_SetSwChnlCmdArray (PreCommonCmd, PreCommonCmdCnt++, +rtl8192_phy_SetSwChnlCmdArray (pre_cmd, pre_cmd_cnt++,MAX_PRECMD_CNT ,CMD_ID_END ,0 ,0 ,0 );/* <2> Fill up post common command. */ - PostCommonCmdCnt =0 ; - -rtl8192_phy_SetSwChnlCmdArray (PostCommonCmd, PostCommonCmdCnt++, + post_cmd_cnt =0 ; +rtl8192_phy_SetSwChnlCmdArray (post_cmd, post_cmd_cnt++,MAX_POSTCMD_CNT ,CMD_ID_END ,0 ,0 ,0 );/* <3> Fill up RF dependent command. */ - RfDependCmdCnt =0 ; + rf_cmd_cnt =0 ;switch (priv->rf_chip) {case RF_8225 :if (!(channel >=1 && channel <=14 )) {
@@ -1249,13 +1248,13 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, ret = true; goto out; } -rtl8192_phy_SetSwChnlCmdArray (RfDependCmd, RfDependCmdCnt++, +rtl8192_phy_SetSwChnlCmdArray (rf_cmd, rf_cmd_cnt++,MAX_RFDEPENDCMD_CNT ,CMD_ID_RF_WRITE_REG , rZebra1_Channel,RF_CHANNEL_TABLE_ZEBRA [channel],10 ); -rtl8192_phy_SetSwChnlCmdArray (RfDependCmd, RfDependCmdCnt++, +rtl8192_phy_SetSwChnlCmdArray (rf_cmd, rf_cmd_cnt++,MAX_RFDEPENDCMD_CNT ,CMD_ID_END ,0 ,0 ,0 );break ;
@@ -1269,11 +1268,11 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, ret = true; goto out; } -rtl8192_phy_SetSwChnlCmdArray (RfDependCmd, RfDependCmdCnt++, +rtl8192_phy_SetSwChnlCmdArray (rf_cmd, rf_cmd_cnt++,MAX_RFDEPENDCMD_CNT ,CMD_ID_RF_WRITE_REG , rZebra1_Channel, channel,10 ); -rtl8192_phy_SetSwChnlCmdArray (RfDependCmd, RfDependCmdCnt++, +rtl8192_phy_SetSwChnlCmdArray (rf_cmd, rf_cmd_cnt++,MAX_RFDEPENDCMD_CNT ,CMD_ID_END ,0 ,0 ,0 );break ;
@@ -1290,19 +1289,19 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, do { switch (*stage) { case 0: - CurrentCmd = &PreCommonCmd[*step]; + current_cmd = &pre_cmd[*step]; break; case 1: - CurrentCmd = &RfDependCmd[*step]; + current_cmd = &rf_cmd[*step]; break; case 2: - CurrentCmd = &PostCommonCmd[*step]; + current_cmd = &post_cmd[*step]; break; } - if (CurrentCmd->cmd_id == CMD_ID_END) { + if (current_cmd->cmd_id == CMD_ID_END) { if ((*stage) == 2) { - (*delay) = CurrentCmd->ms_delay; + *delay = current_cmd->ms_delay; ret = true; goto out; }
@@ -1311,31 +1310,31 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,continue ; } -switch (CurrentCmd->cmd_id) { +switch (current_cmd->cmd_id) {case CMD_ID_SET_TX_PWR_LEVEL :if (priv->card_8192_version ==VERSION_819XU_A )/* consider it later! */ rtl8192_SetTxPowerLevel (dev, channel);break ;case CMD_ID_WRITE_PORT_ULONG : -write_nic_dword (dev, CurrentCmd->para_1, - CurrentCmd->para_2); +write_nic_dword (dev, current_cmd->para_1, + current_cmd->para_2);break ;case CMD_ID_WRITE_PORT_USHORT : -write_nic_word (dev, CurrentCmd->para_1, - (u16 )CurrentCmd->para_2); +write_nic_word (dev, current_cmd->para_1, + (u16 )current_cmd->para_2);break ;case CMD_ID_WRITE_PORT_UCHAR : -write_nic_byte (dev, CurrentCmd->para_1, - (u8 )CurrentCmd->para_2); +write_nic_byte (dev, current_cmd->para_1, + (u8 )current_cmd->para_2);break ;case CMD_ID_RF_WRITE_REG :for (e_rfpath =0 ; e_rfpath <RF90_PATH_MAX ; e_rfpath++) {rtl8192_phy_SetRFReg (dev, (enum rf90_radio_path_e )e_rfpath, - CurrentCmd->para_1, + current_cmd->para_1, bZebra1_ChannelNum, - CurrentCmd->para_2); + current_cmd->para_2); }break ;default :
@@ -1345,14 +1344,14 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,break ; }while (true); - (*delay) = CurrentCmd->ms_delay; + *delay = current_cmd->ms_delay; (*step)++; ret = false; out: -kfree (PreCommonCmd); -kfree (PostCommonCmd); -kfree (RfDependCmd); +kfree (pre_cmd); +kfree (post_cmd); +kfree (rf_cmd);return ret; }
--
2.25.1
PATCH v2 2/3 staging/rtl8192u: Initialize variables in the definition block
In reply to Len BakerInitialize the pre_cmd_cnt, post_cmd_cnt and rf_cmd_cnt variables in the definition block as it is not necessary to do this in the middle of the function.
--- drivers/staging/rtl8192u/r819xU_phy.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
drivers/staging/rtl8192u/r819xU_phy.c +3 -6
@@ -1186,11 +1186,11 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, {struct r8192_priv *priv =ieee80211_priv (dev);struct sw_chnl_cmd *pre_cmd; -u32 pre_cmd_cnt; +u32 pre_cmd_cnt =0 ;struct sw_chnl_cmd *post_cmd; -u32 post_cmd_cnt; +u32 post_cmd_cnt =0 ;struct sw_chnl_cmd *rf_cmd; -u32 rf_cmd_cnt; +u32 rf_cmd_cnt =0 ;struct sw_chnl_cmd *current_cmd =NULL ;u8 e_rfpath;bool ret;
@@ -1225,7 +1225,6 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,/* FIXME: need to check whether channel is legal or not here */ /* <1> Fill up pre common command. */ - pre_cmd_cnt =0 ;rtl8192_phy_SetSwChnlCmdArray (pre_cmd, pre_cmd_cnt++,MAX_PRECMD_CNT ,CMD_ID_SET_TX_PWR_LEVEL ,0 ,0 ,0 );
@@ -1233,12 +1232,10 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel, MAX_PRECMD_CNT, CMD_ID_END, 0, 0, 0);/* <2> Fill up post common command. */ - post_cmd_cnt =0 ;rtl8192_phy_SetSwChnlCmdArray (post_cmd, post_cmd_cnt++,MAX_POSTCMD_CNT ,CMD_ID_END ,0 ,0 ,0 );/* <3> Fill up RF dependent command. */ - rf_cmd_cnt =0 ;switch (priv->rf_chip) {case RF_8225 :if (!(channel >=1 && channel <=14 )) {
--
2.25.1
PATCH v2 3/3 staging/rtl8192u: Prefer kcalloc over open coded arithmetic
In reply to Len BakerAs noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors.
In this case these aren't actually dynamic sizes: both sides of the multiplication are constant values. However it is best to refactor these anyway, just to keep the open-coded math idiom out of code.
So, use the purpose specific kcalloc() function instead of the argument size * count in the kzalloc() function.
--- drivers/staging/rtl8192u/r819xU_phy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
drivers/staging/rtl8192u/r819xU_phy.c +3 -3
@@ -1195,17 +1195,17 @@ static u8 rtl8192_phy_SwChnlStepByStep(struct net_device *dev, u8 channel,u8 e_rfpath;bool ret; - pre_cmd =kzalloc (sizeof (*pre_cmd) *MAX_PRECMD_CNT ,GFP_KERNEL ); + pre_cmd =kcalloc (MAX_PRECMD_CNT ,sizeof (*pre_cmd),GFP_KERNEL );if (!pre_cmd)return false; - post_cmd =kzalloc (sizeof (*post_cmd) *MAX_POSTCMD_CNT ,GFP_KERNEL ); + post_cmd =kcalloc (MAX_POSTCMD_CNT ,sizeof (*post_cmd),GFP_KERNEL );if (!post_cmd) {kfree (pre_cmd);return false; } - rf_cmd =kzalloc (sizeof (*rf_cmd) *MAX_RFDEPENDCMD_CNT ,GFP_KERNEL ); + rf_cmd =kcalloc (MAX_RFDEPENDCMD_CNT ,sizeof (*rf_cmd),GFP_KERNEL );if (!rf_cmd) {kfree (pre_cmd);kfree (post_cmd);
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2.25.1