Re: stmmac: platform: fix default values of the filter bins setting

Looks like 571dcfde2371 ("stmmac: platform: fix default values of the
filter bins setting") introduced the following error.  Either

  1) "plat_dat" can never be NULL, and the test and associated code
should be removed, or
  2) "plat_dat" may be NULL, and we may now dereference it and cause an oops.

---------- Forwarded message ----------
From:  <redacted>
Date: Tue, Dec 2, 2014 at 4:16 PM
Subject: New Defects reported by Coverity Scan for Linux
To: bhelgaas@google.com



Hi,

Please find the latest report on new defect(s) introduced to Linux
found with Coverity Scan.

1 new defect(s) introduced to Linux found with Coverity Scan.
5 defect(s), reported by Coverity Scan earlier, were marked fixed in
the recent build analyzed by Coverity Scan.

New defect(s) Reported-by: Coverity Scan
Showing 1 of 1 defect(s)


** CID 1256529:  Dereference before null check  (REVERSE_INULL)
/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c: 275 in
stmmac_pltfr_probe()


________________________________________________________________________________________________________
*** CID 1256529:  Dereference before null check  (REVERSE_INULL)
/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c: 275 in
stmmac_pltfr_probe()
269             plat_dat->multicast_filter_bins = HASH_TABLE_SIZE;
270
271             /* Set default value for unicast filter entries */
272             plat_dat->unicast_filter_entries = 1;
273
274             if (pdev->dev.of_node) {

quoted

quoted

    CID 1256529:  Dereference before null check  (REVERSE_INULL)
    Null-checking "plat_dat" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.

275                     if (!plat_dat)
276                             plat_dat = devm_kzalloc(&pdev->dev,
277                                             sizeof(struct
plat_stmmacenet_data),
278                                             GFP_KERNEL);
279                     if (!plat_dat) {
280                             pr_err("%s: ERROR: no memory", __func__);


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