simple_xattr: permit 0-size extended attributes

If a filesystem uses simple_xattr to support user extended attributes,
LTP setxattr01 and xfstests generic/062 fail with "Cannot allocate
memory": simple_xattr_alloc()'s wrap-around test mistakenly excludes
values of zero size.  Fix that off-by-one (but apparently no filesystem
needs them yet).

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/xattr.c b/fs/xattr.c
index 3377dff..c69e6d4 100644 (file)
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -843,7 +843,7 @@ struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
 
        /* wrap around? */
        len = sizeof(*new_xattr) + size;
-       if (len <= sizeof(*new_xattr))
+       if (len < sizeof(*new_xattr))
                return NULL;
 
        new_xattr = kmalloc(len, GFP_KERNEL);