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fs/posix_acl.c: make posix_acl_create() safer and cleaner

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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 <dan.carpenter@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dan Carpenter 2015-06-19 09:00:55 +10:00 committed by Al Viro
parent 6b6dabc8dc
commit c0c3a718e3
1 changed files with 20 additions and 26 deletions
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46
fs/posix_acl.c
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@ -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;