2024-02-21 23:52:05

by Justin Stitt

Subject: [PATCH v2] scsi: libfc: replace deprecated strncpy with memcpy

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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
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@google.com
---
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 <[email protected]>

2024-03-10 23:05:04

by Martin K. Petersen

Subject: Re: [PATCH v2] scsi: libfc: replace deprecated strncpy with memcpy

On Wed, 21 Feb 2024 23:50:26 +0000, Justin Stitt wrote:

> 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,
> ...
>
> [...]

Applied to 6.9/scsi-queue, thanks!

[1/1] scsi: libfc: replace deprecated strncpy with memcpy
https://git.kernel.org/mkp/scsi/c/3e24118ec185

--
Martin K. Petersen Oracle Linux Engineering