scsi: ibmvscsi_tgt: Replace deprecated strncpy() with strscpy()

strncpy() is deprecated for use on NUL-terminated destination strings [1]
and as such we should prefer more robust and less ambiguous string
interfaces.

We don't need the NUL-padding behavior that strncpy() provides as vscsi is
NUL-allocated in ibmvscsis_probe() which proceeds to call
ibmvscsis_adapter_info():

|       vscsi = kzalloc(sizeof(*vscsi), GFP_KERNEL);

ibmvscsis_probe() -> ibmvscsis_handle_crq() -> ibmvscsis_parse_command()
-> ibmvscsis_mad() -> ibmvscsis_process_mad() -> ibmvscsis_adapter_info()

Following the same idea, `partition_name` is defiend as:

|       static char partition_name[PARTITION_NAMELEN] = "UNKNOWN";
... which is NUL-padded already, meaning strscpy() is the best option.

Considering the above, a suitable replacement is strscpy() [2] due to the
fact that it guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

However, for cap->name and info let's use strscpy_pad() as they are
allocated via dma_alloc_coherent():

|       cap = dma_alloc_coherent(&vscsi->dma_dev->dev, olen, &token,
|                                GFP_ATOMIC);
&
|       info = dma_alloc_coherent(&vscsi->dma_dev->dev, sizeof(*info), &token,
|                                 GFP_ATOMIC);

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20231212-strncpy-drivers-scsi-ibmvscsi_tgt-ibmvscsi_tgt-c-v2-1-bdb9a7cd96c8@google.com
Acked-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
index 4dc411a58107010dca5ddb73e54ebc231c679631..6b16020b1f5984642bee2da319ec4029de7e501e 100644 (file)
--- a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
+++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
@@ -1551,18 +1551,18 @@ static long ibmvscsis_adapter_info(struct scsi_info *vscsi,
        if (vscsi->client_data.partition_number == 0)
                vscsi->client_data.partition_number =
                        be32_to_cpu(info->partition_number);
-       strncpy(vscsi->client_data.srp_version, info->srp_version,
+       strscpy(vscsi->client_data.srp_version, info->srp_version,
                sizeof(vscsi->client_data.srp_version));
-       strncpy(vscsi->client_data.partition_name, info->partition_name,
+       strscpy(vscsi->client_data.partition_name, info->partition_name,
                sizeof(vscsi->client_data.partition_name));
        vscsi->client_data.mad_version = be32_to_cpu(info->mad_version);
        vscsi->client_data.os_type = be32_to_cpu(info->os_type);
 
        /* Copy our info */
-       strncpy(info->srp_version, SRP_VERSION,
-               sizeof(info->srp_version));
-       strncpy(info->partition_name, vscsi->dds.partition_name,
-               sizeof(info->partition_name));
+       strscpy_pad(info->srp_version, SRP_VERSION,
+                   sizeof(info->srp_version));
+       strscpy_pad(info->partition_name, vscsi->dds.partition_name,
+                   sizeof(info->partition_name));
        info->partition_number = cpu_to_be32(vscsi->dds.partition_num);
        info->mad_version = cpu_to_be32(MAD_VERSION_1);
        info->os_type = cpu_to_be32(LINUX);
@@ -1645,8 +1645,8 @@ static int ibmvscsis_cap_mad(struct scsi_info *vscsi, struct iu_entry *iue)
                         be64_to_cpu(mad->buffer),
                         vscsi->dds.window[LOCAL].liobn, token);
        if (rc == H_SUCCESS) {
-               strncpy(cap->name, dev_name(&vscsi->dma_dev->dev),
-                       SRP_MAX_LOC_LEN);
+               strscpy_pad(cap->name, dev_name(&vscsi->dma_dev->dev),
+                       sizeof(cap->name));
 
                len = olen - min_len;
                status = VIOSRP_MAD_SUCCESS;
@@ -3650,7 +3650,7 @@ static int ibmvscsis_get_system_info(void)
 
        name = of_get_property(rootdn, "ibm,partition-name", NULL);
        if (name)
-               strncpy(partition_name, name, sizeof(partition_name));
+               strscpy(partition_name, name, sizeof(partition_name));
 
        num = of_get_property(rootdn, "ibm,partition-no", NULL);
        if (num)