9p: v9fs_listxattr: fix %s null argument warning

W=1 warns about null argument to kprintf:
In file included from fs/9p/xattr.c:12:
In function ‘v9fs_xattr_get’,
    inlined from ‘v9fs_listxattr’ at fs/9p/xattr.c:142:9:
include/net/9p/9p.h:55:2: error: ‘%s’ directive argument is null
[-Werror=format-overflow=]
   55 |  _p9_debug(level, __func__, fmt, ##__VA_ARGS__)
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use an empty string instead of :
 - this is ok 9p-wise because p9pdu_vwritef serializes a null string
and an empty string the same way (one '0' word for length)
 - since this degrades the print statements, add new single quotes for
xattr's name delimter (Old: "file = (null)", new: "file = ''")

Link: https://lore.kernel.org/r/20231008060138.517057-1-suhui@nfschina.com
Suggested-by: Su Hui <suhui@nfschina.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Acked-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Message-ID: <20231025103445.1248103-2-asmadeus@codewreck.org>

diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
index e00cf8109b3f31cb77ffb900b56ca67df480a791..3c4572ef3a488a8ed809bcd31983cc0360cf5c3c 100644 (file)
--- a/fs/9p/xattr.c
+++ b/fs/9p/xattr.c
@@ -68,7 +68,7 @@ ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
        struct p9_fid *fid;
        int ret;
 
-       p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
+       p9_debug(P9_DEBUG_VFS, "name = '%s' value_len = %zu\n",
                 name, buffer_size);
        fid = v9fs_fid_lookup(dentry);
        if (IS_ERR(fid))
@@ -139,7 +139,8 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 
 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 {
-       return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
+       /* Txattrwalk with an empty string lists xattrs instead */
+       return v9fs_xattr_get(dentry, "", buffer, buffer_size);
 }
 
 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,

diff --git a/net/9p/client.c b/net/9p/client.c
index 86bbc7147fc148822e2b39b6aa0ce291c197ed4f..9c2bc15e3cfaf0a206468697b047632083a80558 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1979,7 +1979,7 @@ struct p9_fid *p9_client_xattrwalk(struct p9_fid *file_fid,
                goto error;
        }
        p9_debug(P9_DEBUG_9P,
-                ">>> TXATTRWALK file_fid %d, attr_fid %d name %s\n",
+                ">>> TXATTRWALK file_fid %d, attr_fid %d name '%s'\n",
                 file_fid->fid, attr_fid->fid, attr_name);
 
        req = p9_client_rpc(clnt, P9_TXATTRWALK, "dds",