On 03/11/2018 08:43 PM, Tobin C. Harding wrote:
The kernel would like to have all stack VLA usage removed[1].  rsi uses
a VLA based on 'blksize'.  Elsewhere in the SDIO code maximum block size
is defined using a magic number.  We can use a pre-processor defined
constant and declare the array to maximum size.  We add a check before
accessing the array in case of programmer error.

[1]: https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Tobin C. Harding <m...@tobin.cc>
---

RESEND: add wireless mailing list to CC's (requested by Kalle)

  drivers/net/wireless/rsi/rsi_91x_hal.c  | 13 +++++++------
  drivers/net/wireless/rsi/rsi_91x_sdio.c |  9 +++++++--
  2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/rsi/rsi_91x_hal.c 
b/drivers/net/wireless/rsi/rsi_91x_hal.c
index 1176de646942..839ebdd602df 100644
--- a/drivers/net/wireless/rsi/rsi_91x_hal.c
+++ b/drivers/net/wireless/rsi/rsi_91x_hal.c
@@ -641,7 +641,7 @@ static int ping_pong_write(struct rsi_hw *adapter, u8 cmd, 
u8 *addr, u32 size)
        u32 cmd_addr;
        u16 cmd_resp, cmd_req;
        u8 *str;
-       int status;
+       int status, ret;
if (cmd == PING_WRITE) {
                cmd_addr = PING_BUFFER_ADDRESS;
@@ -655,12 +655,13 @@ static int ping_pong_write(struct rsi_hw *adapter, u8 
cmd, u8 *addr, u32 size)
                str = "PONG_VALID";
        }
- status = hif_ops->load_data_master_write(adapter, cmd_addr, size,
+       ret = hif_ops->load_data_master_write(adapter, cmd_addr, size,
                                            block_size, addr);
-       if (status) {
-               rsi_dbg(ERR_ZONE, "%s: Unable to write blk at addr %0x\n",
-                       __func__, *addr);
-               return status;
+       if (ret) {
+               if (ret != -EINVAL)
+                       rsi_dbg(ERR_ZONE, "%s: Unable to write blk at addr 
%0x\n",
+                               __func__, *addr);
+               return ret;
        }
status = bl_cmd(adapter, cmd_req, cmd_resp, str);
diff --git a/drivers/net/wireless/rsi/rsi_91x_sdio.c 
b/drivers/net/wireless/rsi/rsi_91x_sdio.c
index b0cf41195051..b766578b591a 100644
--- a/drivers/net/wireless/rsi/rsi_91x_sdio.c
+++ b/drivers/net/wireless/rsi/rsi_91x_sdio.c
@@ -20,6 +20,8 @@
  #include "rsi_common.h"
  #include "rsi_hal.h"
+#define RSI_MAX_BLOCK_SIZE 256
+
  /**
   * rsi_sdio_set_cmd52_arg() - This function prepares cmd 52 read/write arg.
   * @rw: Read/write
@@ -362,7 +364,7 @@ static int rsi_setblocklength(struct rsi_hw *adapter, u32 
length)
        rsi_dbg(INIT_ZONE, "%s: Setting the block length\n", __func__);
status = sdio_set_block_size(dev->pfunction, length);
-       dev->pfunction->max_blksize = 256;
+       dev->pfunction->max_blksize = RSI_MAX_BLOCK_SIZE;
        adapter->block_size = dev->pfunction->max_blksize;
rsi_dbg(INFO_ZONE,
@@ -567,9 +569,12 @@ static int rsi_sdio_load_data_master_write(struct rsi_hw 
*adapter,
  {
        u32 num_blocks, offset, i;
        u16 msb_address, lsb_address;
-       u8 temp_buf[block_size];
+       u8 temp_buf[RSI_MAX_BLOCK_SIZE];
        int status;
+ if (block_size > RSI_MAX_BLOCK_SIZE)
+               return -EINVAL;
+
        num_blocks = instructions_sz / block_size;
        msb_address = base_address >> 16;

I am not giving this patch a negative review, but my solution to the same problem has been to change the on-stack array into a u8 pointer, use kmalloc() to assign the space, and then free that space at the end. That way large stack allocations are avoided, with a minimum of changes.

Larry


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