From c0c3a718e3ab2430a52a60d614b109e5e48e83e2 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 19 Jun 2015 09:00:55 +1000 Subject: [PATCH] fs/posix_acl.c: make posix_acl_create() safer and cleaner If posix_acl_create() returns an error code then "*acl" and "*default_acl" can be uninitialized or point to freed memory. This is a dangerous thing to do. For example, it causes a problem in ocfs2_reflink(): fs/ocfs2/refcounttree.c:4327 ocfs2_reflink() error: potentially using uninitialized 'default_acl'. I've re-written this so we set the pointers to NULL at the start. I've added a temporary "clone" variable to hold the value of "*acl" until end. Setting them to NULL means means we don't need the "no_acl" label. We may as well remove the "apply_umask" stuff forward and remove that label as well. Signed-off-by: Dan Carpenter Cc: Alexander Viro Cc: Joel Becker Cc: Mark Fasheh Signed-off-by: Andrew Morton --- fs/posix_acl.c | 46 ++++++++++++++++++++-------------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index 84bb65b83570..4fb17ded7d47 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -547,51 +547,45 @@ posix_acl_create(struct inode *dir, umode_t *mode, struct posix_acl **default_acl, struct posix_acl **acl) { struct posix_acl *p; + struct posix_acl *clone; int ret; + *acl = NULL; + *default_acl = NULL; + if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) - goto no_acl; + return 0; p = get_acl(dir, ACL_TYPE_DEFAULT); - if (IS_ERR(p)) { - if (p == ERR_PTR(-EOPNOTSUPP)) - goto apply_umask; - return PTR_ERR(p); + if (!p || p == ERR_PTR(-EOPNOTSUPP)) { + *mode &= ~current_umask(); + return 0; } + if (IS_ERR(p)) + return PTR_ERR(p); - if (!p) - goto apply_umask; - - *acl = posix_acl_clone(p, GFP_NOFS); - if (!*acl) + clone = posix_acl_clone(p, GFP_NOFS); + if (!clone) goto no_mem; - ret = posix_acl_create_masq(*acl, mode); + ret = posix_acl_create_masq(clone, mode); if (ret < 0) goto no_mem_clone; - if (ret == 0) { - posix_acl_release(*acl); - *acl = NULL; - } + if (ret == 0) + posix_acl_release(clone); + else + *acl = clone; - if (!S_ISDIR(*mode)) { + if (!S_ISDIR(*mode)) posix_acl_release(p); - *default_acl = NULL; - } else { + else *default_acl = p; - } - return 0; -apply_umask: - *mode &= ~current_umask(); -no_acl: - *default_acl = NULL; - *acl = NULL; return 0; no_mem_clone: - posix_acl_release(*acl); + posix_acl_release(clone); no_mem: posix_acl_release(p); return -ENOMEM;