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From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Sat, 9 Feb 2019 09:51:11 +1000
Subject: [PATCH] cifs: replace snprintf with scnprintf
Git-commit: 74ea5f983f9e86ebb4b7ed611937776dab18c67e
Patch-mainline: v5.1-rc1
References: bsc#1144333

a trivial patch that replaces all use of snprintf with scnprintf.
scnprintf() is generally seen as a safer function to use than
snprintf for many use cases.

In our case, there is no actual difference between the two since we never
look at the return value. Thus we did not have any of the bugs that
scnprintf protects against and the patch does nothing.

However, for people reading our code it will be a receipt that we
have done our due dilligence and checked our code for this type of bugs.

See the presentation "Making C Less Dangerous In The Linux Kernel"
at this years LCA

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifssmb.c   |  6 +++---
 fs/cifs/connect.c   |  6 +++---
 fs/cifs/link.c      | 14 +++++++-------
 fs/cifs/smb2pdu.c   |  6 +++---
 fs/cifs/smbdirect.c |  6 +++---
 5 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 551924beb86f..6bd3605b9b65 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -139,8 +139,8 @@ static int __cifs_reconnect_tcon(const struct nls_table *nlsc,
 		return -ENOMEM;
 
 	if (tcon->ipc) {
-		snprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$",
-			 tcon->ses->server->hostname);
+		scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$",
+			  tcon->ses->server->hostname);
 		rc = CIFSTCon(0, tcon->ses, tree, tcon, nlsc);
 		goto out;
 	}
@@ -172,7 +172,7 @@ static int __cifs_reconnect_tcon(const struct nls_table *nlsc,
 			continue;
 		}
 
-		snprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
+		scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
 
 		rc = CIFSTCon(0, tcon->ses, tree, tcon, nlsc);
 		if (!rc)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 2ed773b395a4..7c9108ce3de0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -348,7 +348,7 @@ static int reconn_set_ipaddr(struct TCP_Server_Info *server)
 		cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
 		return -ENOMEM;
 	}
-	snprintf(unc, len, "\\\\%s", server->hostname);
+	scnprintf(unc, len, "\\\\%s", server->hostname);
 
 	rc = dns_resolve_server_name_to_ip(unc, &ipaddr);
 	kfree(unc);
@@ -2775,7 +2775,7 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb_vol *volume_info)
 	if (tcon == NULL)
 		return -ENOMEM;
 
-	snprintf(unc, sizeof(unc), "\\\\%s\\IPC$", ses->server->hostname);
+	scnprintf(unc, sizeof(unc), "\\\\%s\\IPC$", ses->server->hostname);
 
 	/* cannot fail */
 	nls_codepage = load_nls_default();
@@ -4203,7 +4203,7 @@ static int update_vol_info(const struct dfs_cache_tgt_iterator *tgt_it,
 	new_unc = kmalloc(len, GFP_KERNEL);
 	if (!new_unc)
 		return -ENOMEM;
-	snprintf(new_unc, len, "\\%s", tgt);
+	scnprintf(new_unc, len, "\\%s", tgt);
 
 	kfree(vol->UNC);
 	vol->UNC = new_unc;
diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 2148b0f60e5e..62216dc8f9f5 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -103,9 +103,9 @@ parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
 		return rc;
 	}
 
-	snprintf(md5_str2, sizeof(md5_str2),
-		 CIFS_MF_SYMLINK_MD5_FORMAT,
-		 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
+	scnprintf(md5_str2, sizeof(md5_str2),
+		  CIFS_MF_SYMLINK_MD5_FORMAT,
+		  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 
 	if (strncmp(md5_str1, md5_str2, 17) != 0)
 		return -EINVAL;
@@ -142,10 +142,10 @@ format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
 		return rc;
 	}
 
-	snprintf(buf, buf_len,
-		 CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
-		 link_len,
-		 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
+	scnprintf(buf, buf_len,
+		  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
+		  link_len,
+		  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 
 	ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 	memcpy(buf + ofs, link_str, link_len);
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 77b3aaa39b35..7d9a1cb9ecae 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -173,8 +173,8 @@ static int __smb2_reconnect(const struct nls_table *nlsc,
 		return -ENOMEM;
 
 	if (tcon->ipc) {
-		snprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$",
-			 tcon->ses->server->hostname);
+		scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$",
+			  tcon->ses->server->hostname);
 		rc = SMB2_tcon(0, tcon->ses, tree, tcon, nlsc);
 		goto out;
 	}
@@ -206,7 +206,7 @@ static int __smb2_reconnect(const struct nls_table *nlsc,
 			continue;
 		}
 
-		snprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
+		scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
 
 		rc = SMB2_tcon(0, tcon->ses, tree, tcon, nlsc);
 		if (!rc)
diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index a568dac7b3a1..b943b74cd246 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -1550,7 +1550,7 @@ static int allocate_caches_and_workqueue(struct smbd_connection *info)
 	char name[MAX_NAME_LEN];
 	int rc;
 
-	snprintf(name, MAX_NAME_LEN, "smbd_request_%p", info);
+	scnprintf(name, MAX_NAME_LEN, "smbd_request_%p", info);
 	info->request_cache =
 		kmem_cache_create(
 			name,
@@ -1566,7 +1566,7 @@ static int allocate_caches_and_workqueue(struct smbd_connection *info)
 	if (!info->request_mempool)
 		goto out1;
 
-	snprintf(name, MAX_NAME_LEN, "smbd_response_%p", info);
+	scnprintf(name, MAX_NAME_LEN, "smbd_response_%p", info);
 	info->response_cache =
 		kmem_cache_create(
 			name,
@@ -1582,7 +1582,7 @@ static int allocate_caches_and_workqueue(struct smbd_connection *info)
 	if (!info->response_mempool)
 		goto out3;
 
-	snprintf(name, MAX_NAME_LEN, "smbd_%p", info);
+	scnprintf(name, MAX_NAME_LEN, "smbd_%p", info);
 	info->workqueue = create_workqueue(name);
 	if (!info->workqueue)
 		goto out4;
-- 
2.16.4