linux-kernel - [PATCH 13/20] scsi: zfcp: Manual replacement of the deprecated strlcpy() with return values

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Date:   Mon, 22 Feb 2021 16:12:24 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        Steffen Maier <maier@...ux.ibm.com>,
        Benjamin Block <bblock@...ux.ibm.com>
Cc:     Romain Perier <romain.perier@...il.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 13/20] scsi: zfcp: Manual replacement of the deprecated strlcpy() with return values

The strlcpy() reads the entire source buffer first, it is dangerous if
the source buffer lenght is unbounded or possibility non NULL-terminated.
It can lead to linear read overflows, crashes, etc...

As recommended in the deprecated interfaces [1], it should be replaced
by strscpy.

This commit replaces all calls to strlcpy that handle the return values
by the corresponding strscpy calls with new handling of the return
values (as it is quite different between the two functions).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy

Signed-off-by: Romain Perier <romain.perier@...il.com>
---
 drivers/s390/scsi/zfcp_fc.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index d24cafe02708..8a65241011b9 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -877,14 +877,16 @@ static void zfcp_fc_rspn(struct zfcp_adapter *adapter,
 	struct zfcp_fsf_ct_els *ct_els = &fc_req->ct_els;
 	struct zfcp_fc_rspn_req *rspn_req = &fc_req->u.rspn.req;
 	struct fc_ct_hdr *rspn_rsp = &fc_req->u.rspn.rsp;
-	int ret, len;
+	int ret;
+	ssize_t len;
 
 	zfcp_fc_ct_ns_init(&rspn_req->ct_hdr, FC_NS_RSPN_ID,
 			   FC_SYMBOLIC_NAME_SIZE);
 	hton24(rspn_req->rspn.fr_fid.fp_fid, fc_host_port_id(shost));
-	len = strlcpy(rspn_req->rspn.fr_name, fc_host_symbolic_name(shost),
+	len = strscpy(rspn_req->rspn.fr_name, fc_host_symbolic_name(shost),
 		      FC_SYMBOLIC_NAME_SIZE);
-	rspn_req->rspn.fr_name_len = len;
+	if (len != -E2BIG)
+		rspn_req->rspn.fr_name_len = len;
 
 	sg_init_one(&fc_req->sg_req, rspn_req, sizeof(*rspn_req));
 	sg_init_one(&fc_req->sg_rsp, rspn_rsp, sizeof(*rspn_rsp));