strncpy() is deprecated [1] and as such we should use different apis to
copy string data.
We can see that ct is NUL-initialized with fc_ct_hdr_fill:
| ct = fc_ct_hdr_fill(fp, op, sizeof(struct fc_ns_rspn) + len,
...
In fc_ct_hdr_fill():
| memset(ct, 0, ct_plen);
We also calculate the length of the source string:
| len = strnlen(fc_host_symbolic_name(lport->host), 255);
...then this argument is used in strncpy(), which is bad because the
pattern of (dest, src, strlen(src)) usually leaves the destination
buffer without NUL-termination. However, it looks as though we do not
require NUL-termination since fr_name is part of a seq_buf-like
structure wherein its length is monitored:
| struct fc_ns_rspn {
| struct fc_ns_fid fr_fid; /* port ID object */
| __u8 fr_name_len;
| char fr_name[];
| } __attribute__((__packed__));
So, this is really just a byte copy into a length-bounded buffer. Let's
use memcpy().
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Changes in v2:
- Don't mark fields with __nonstring
- Link to v1: https://lore.kernel.org/r/20231030-strncpy-drivers-scsi-libfc-fc_encode-h-v1-1-c08c2be6befa@xxxxxxxxxx
---
drivers/scsi/libfc/fc_encode.h | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/libfc/fc_encode.h b/drivers/scsi/libfc/fc_encode.h
index 7dcac3b6baa7..6b7e4ca6b7b5 100644
--- a/drivers/scsi/libfc/fc_encode.h
+++ b/drivers/scsi/libfc/fc_encode.h
@@ -136,22 +136,24 @@ static inline int fc_ct_ns_fill(struct fc_lport *lport,
break;
case FC_NS_RSPN_ID:
- len = strnlen(fc_host_symbolic_name(lport->host), 255);
+ len = strnlen(fc_host_symbolic_name(lport->host),
+ FC_SYMBOLIC_NAME_SIZE);
ct = fc_ct_hdr_fill(fp, op, sizeof(struct fc_ns_rspn) + len,
FC_FST_DIR, FC_NS_SUBTYPE);
hton24(ct->payload.spn.fr_fid.fp_fid, lport->port_id);
- strncpy(ct->payload.spn.fr_name,
- fc_host_symbolic_name(lport->host), len);
+ memcpy(ct->payload.spn.fr_name,
+ fc_host_symbolic_name(lport->host), len);
ct->payload.spn.fr_name_len = len;
break;
case FC_NS_RSNN_NN:
- len = strnlen(fc_host_symbolic_name(lport->host), 255);
+ len = strnlen(fc_host_symbolic_name(lport->host),
+ FC_SYMBOLIC_NAME_SIZE);
ct = fc_ct_hdr_fill(fp, op, sizeof(struct fc_ns_rsnn) + len,
FC_FST_DIR, FC_NS_SUBTYPE);
put_unaligned_be64(lport->wwnn, &ct->payload.snn.fr_wwn);
- strncpy(ct->payload.snn.fr_name,
- fc_host_symbolic_name(lport->host), len);
+ memcpy(ct->payload.snn.fr_name,
+ fc_host_symbolic_name(lport->host), len);
ct->payload.snn.fr_name_len = len;
break;
---
base-commit: 517bc069e3eaad84d879101e0351ca7783243b32
change-id: 20231030-strncpy-drivers-scsi-libfc-fc_encode-h-5ad629f6de9c
Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>
