[PATCH] ibmvnic: fix krealloc() memory leak

[Alexander A. Klimov]

Don't just overwrite the original pointer passed to krealloc()
with its return value without checking latter:

    MEM = krealloc(MEM, SZ, GFP);

If krealloc() returns NULL, that erases the pointer
to the still allocated memory, hence leaks this memory.
Instead, use a temporary variable, check it's not NULL
and only then assign it to the original pointer:

    TMP = krealloc(MEM, SZ, GFP);
    if (!TMP) return;
    MEM = TMP;

Fixes: 4e6759be28e4 ("ibmvnic: Feature implementation of Vital Product Data 
(VPD) for the ibmvnic driver")
Signed-off-by: Alexander A. Klimov <grandmas...@al2klimov.de>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c 
b/drivers/net/ethernet/ibm/ibmvnic.c
index 5a510eed335e..25d1d844ad19 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1761,8 +1761,9 @@ static int ibmvnic_get_vpd(struct ibmvnic_adapter 
*adapter)
        union ibmvnic_crq crq;
        int len = 0;
        int rc;
+       unsigned char *buff = adapter->vpd->buff;
 
-       if (adapter->vpd->buff)
+       if (buff)
                len = adapter->vpd->len;
 
        mutex_lock(&adapter->fw_lock);
@@ -1788,17 +1789,17 @@ static int ibmvnic_get_vpd(struct ibmvnic_adapter 
*adapter)
        if (!adapter->vpd->len)
                return -ENODATA;
 
-       if (!adapter->vpd->buff)
-               adapter->vpd->buff = kzalloc(adapter->vpd->len, GFP_KERNEL);
+       if (!buff)
+               buff = kzalloc(adapter->vpd->len, GFP_KERNEL);
        else if (adapter->vpd->len != len)
-               adapter->vpd->buff =
-                       krealloc(adapter->vpd->buff,
-                                adapter->vpd->len, GFP_KERNEL);
+               buff = krealloc(buff,
+                               adapter->vpd->len, GFP_KERNEL);
 
-       if (!adapter->vpd->buff) {
+       if (!buff) {
                dev_err(dev, "Could allocate VPD buffer\n");
                return -ENOMEM;
        }
+       adapter->vpd->buff = buff;
 
        adapter->vpd->dma_addr =
                dma_map_single(dev, adapter->vpd->buff, adapter->vpd->len,
-- 
2.54.0