[Ocfs2-devel] [PATCH v2] ocfs2: fix warning 'ocfs2_orphan_del' uses dynamic stack allocation
Joseph Qi
joseph.qi at huawei.com
Tue Mar 10 23:16:53 PDT 2015
Hi Andrew,
On 2015/1/27 6:38, Andrew Morton wrote:
> On Mon, 26 Jan 2015 11:20:47 +0800 Joseph Qi <joseph.qi at huawei.com> wrote:
>
>> In ocfs2_orphan_del it uses dynamic stack allocation for orphan entry
>> name. Fix it by using dynamic heap allocation.
>>
>> ...
>>
>> --- a/fs/ocfs2/namei.c
>> +++ b/fs/ocfs2/namei.c
>> @@ -2298,18 +2298,22 @@ int ocfs2_orphan_del(struct ocfs2_super *osb,
>> {
>> int namelen = dio ? OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN :
>> OCFS2_ORPHAN_NAMELEN;
>> - char name[namelen + 1];
>> + char *name;
>> struct ocfs2_dinode *orphan_fe;
>> int status = 0;
>> struct ocfs2_dir_lookup_result lookup = { NULL, };
>>
>> + name = kmalloc(namelen + 1, GFP_NOFS);
>> + if (!name)
>> + goto leave;
>> +
>> if (dio) {
>> status = snprintf(name, OCFS2_DIO_ORPHAN_PREFIX_LEN + 1, "%s",
>> OCFS2_DIO_ORPHAN_PREFIX);
>> if (status != OCFS2_DIO_ORPHAN_PREFIX_LEN) {
>> status = -EINVAL;
>> mlog_errno(status);
>> - return status;
>> + goto leave;
>> }
>>
>> status = ocfs2_blkno_stringify(OCFS2_I(inode)->ip_blkno,
>> @@ -2357,6 +2361,7 @@ int ocfs2_orphan_del(struct ocfs2_super *osb,
>> ocfs2_journal_dirty(handle, orphan_dir_bh);
>>
>> leave:
>> + kfree(name);
>> ocfs2_free_dir_lookup_result(&lookup);
>>
>> if (status)
>
> I think I prefer my fix:
>
> --- a/fs/ocfs2/namei.c~ocfs2-add-functions-to-add-and-remove-inode-in-orphan-dir-fix
> +++ a/fs/ocfs2/namei.c
> @@ -2296,8 +2296,7 @@ int ocfs2_orphan_del(struct ocfs2_super
> struct buffer_head *orphan_dir_bh,
> bool dio)
> {
> - int namelen = dio ? OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN :
> - OCFS2_ORPHAN_NAMELEN;
> + const int namelen = OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN;
> char name[namelen + 1];
> struct ocfs2_dinode *orphan_fe;
> int status = 0;
>
> It means we use 20 bytes of stack all the time, instead of
> sometimes-20, sometimes-16.
>
> .
>
If so, the namelen being passed to ocfs2_find_entry should be the
actual name length. Otherwise, it will fail because of mismatch.
I'll send a patch to fix this.
More information about the Ocfs2-devel
mailing list