[PATCH] staging: r8822be: check kzalloc return or bail

[PATCH] staging: r8822be: check kzalloc return or bail

[Nicholas Mc Guire]

The kzalloc() in halmac_parse_psd_data_88xx() can fail and return NULL
so check the psd_set->data after allocation and if allocation failed
return HALMAC_CMD_PROCESS_ERROR.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: 938a0447f094 ("staging: r8822be: Add code for halmac sub-drive")
---

Problem was located with an experimental coccinelle script

Patch was compile tested with: x86_64_defconfig + STAGING=y,
R8822BE=m
(with a smatch error that looks like a false-positive

  CHECK   drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c:624 halmac_func_write_logical_efuse_88xx() error: uninitialized symbol 'pg_efuse_header2'.
  CC [M]  drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.o

as the initialization of pg_efuse_header2 is under the same if condition (line 592) as the
use at line 624 it is initialized)

Patch is agaisnt 5.0-rc6 (localversion-next is next-20190215)

 drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
index 53f55f12..bf783a0 100644
--- a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
+++ b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
@@ -2466,8 +2466,11 @@ halmac_parse_psd_data_88xx(struct halmac_adapter *halmac_adapter, u8 *c2h_buf,
 	segment_size = (u8)PSD_DATA_GET_SEGMENT_SIZE(c2h_buf);
 	psd_set->data_size = total_size;
 
-	if (!psd_set->data)
+	if (!psd_set->data) {
 		psd_set->data = kzalloc(psd_set->data_size, GFP_KERNEL);
+		if (!psd_set->data)
+			return HALMAC_CMD_PROCESS_ERROR;
+	}
 
 	if (segment_id == 0)
 		psd_set->segment_size = segment_size;
-- 
2.1.4

Re: [PATCH] staging: r8822be: check kzalloc return or bail

[Dan Carpenter]

On Fri, Feb 15, 2019 at 10:24:22AM +0100, Nicholas Mc Guire wrote:
> The kzalloc() in halmac_parse_psd_data_88xx() can fail and return NULL
> so check the psd_set->data after allocation and if allocation failed
> return HALMAC_CMD_PROCESS_ERROR.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> Fixes: 938a0447f094 ("staging: r8822be: Add code for halmac sub-drive")
> ---
> 
> Problem was located with an experimental coccinelle script
> 
> Patch was compile tested with: x86_64_defconfig + STAGING=y,
> R8822BE=m
> (with a smatch error that looks like a false-positive
> 
>   CHECK   drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
> drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c:624 halmac_func_write_logical_efuse_88xx() error: uninitialized symbol 'pg_efuse_header2'.
>   CC [M]  drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.o
> 
> as the initialization of pg_efuse_header2 is under the same if condition (line 592) as the
> use at line 624 it is initialized)
>

Hm...  That's tricky code for Smatch to parse.

drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
   592                  if (offset > 0x7f) {
   593                          pg_efuse_header =
   594                                  (((pg_block & 0x07) << 5) & 0xE0) | 0x0F;
   595                          pg_efuse_header2 =
                                ^^^^^^^^^^^^^^^^^^
pg_efuse_header2 is only intialized on this path.

   596                                  (u8)(((pg_block & 0x78) << 1) +
   597                                       ((0x1 << pg_block_index) ^ 0x0F));
   598                  } else {
   599                          pg_efuse_header =
   600                                  (u8)((pg_block << 4) +
   601                                       ((0x01 << pg_block_index) ^ 0x0F));
   602                  }
   603  
   604                  if ((offset & 1) == 0) {
                            ^^^^^^^^^^^^^^^^^
But this condition confuses Smatch.  Smatch marks it as saying that
offset is non-zero on this size.

   605                          pg_efuse_byte1 = value;
   606                          pg_efuse_byte2 = *(eeprom_map + offset + 1);
   607                  } else {

And this side offset = 0-0x7e.

   608                          pg_efuse_byte1 = *(eeprom_map + offset - 1);
   609                          pg_efuse_byte2 = value;
   610                  }
   611  
   612                  if (offset > 0x7f) {
                            ^^^^^^^^^^^^^
So it doesn't parse this condition correctly.

   613                          pg_efuse_num = 4;
   614                          if (halmac_adapter->hw_config_info.efuse_size <=
   615                              (pg_efuse_num + HALMAC_PROTECTED_EFUSE_SIZE_88XX +
   616                               halmac_adapter->efuse_end)) {
   617                                  kfree(eeprom_map);
   618                                  return HALMAC_RET_EFUSE_NOT_ENOUGH;
   619                          }
   620                          halmac_func_write_efuse_88xx(halmac_adapter, efuse_end,
   621                                                       pg_efuse_header);
   622                          halmac_func_write_efuse_88xx(halmac_adapter,
   623                                                       efuse_end + 1,
   624                                                       pg_efuse_header2);
                                                             ^^^^^^^^^^^^^^^^
And it warns here.

   625                          halmac_func_write_efuse_88xx(
   626                                  halmac_adapter, efuse_end + 2, pg_efuse_byte1);
   627                          status = halmac_func_write_efuse_88xx(
   628                                  halmac_adapter, efuse_end + 3, pg_efuse_byte2);


It should be possible to fix this false positive...  It's just a matter
of doing the work.

regards,
dan carpenter