[PATCH] ata: libata-core: Fix possible null-pointer dereferences in ata_host_alloc_pinfo()

[Jia-Ju Bai]

In ata_host_alloc_pinfo(), when ppi[j] is NULL (line 6184), pi is NULL.
In this case, pi is used on lines 6187-6195:
    ap->pio_mask = pi->pio_mask;
    ap->mwdma_mask = pi->mwdma_mask;
    ...
Thus, possible null-pointer dereferences may occur.

To fix these possible bugs, when ppi[j] is NULL, the loop continues, and
"j++" is moved to the loop's regulator.

These bugs are found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1...@gmail.com>
---
 drivers/ata/libata-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 28c492be0a57..dabfa50dfbbe 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6178,11 +6178,13 @@ struct ata_host *ata_host_alloc_pinfo(struct device 
*dev,
        if (!host)
                return NULL;
 
-       for (i = 0, j = 0, pi = NULL; i < host->n_ports; i++) {
+       for (i = 0, j = 0, pi = NULL; i < host->n_ports; i++, j++) {
                struct ata_port *ap = host->ports[i];
 
                if (ppi[j])
-                       pi = ppi[j++];
+                       pi = ppi[j];
+               else
+                       continue;
 
                ap->pio_mask = pi->pio_mask;
                ap->mwdma_mask = pi->mwdma_mask;
-- 
2.17.0