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scsi: libfc: replace deprecated strncpy() with memcpy()

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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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240221-strncpy-drivers-scsi-libfc-fc_encode-h-v2-1-019a0889c5ca@google.com
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Justin Stitt 2024-02-21 23:50:26 +00:00 committed by Martin K. Petersen
parent e100c01efa
commit 3e24118ec1
1 changed files with 8 additions and 6 deletions
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14
drivers/scsi/libfc/fc_encode.h
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@ -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;