On 03/16/2013 11:58 AM, Ming Lei wrote:
> On Sat, Mar 16, 2013 at 11:22 PM, Ming Lei <tom.leim...@gmail.com> wrote:
>> On Sat, Mar 16, 2013 at 11:07 PM, Sasha Levin <levinsasha...@gmail.com>
>> wrote:
>>>
>>> Hi Ming,
>>>
>>> With your patch:
>>>
>>>
>>> [ 1525.874312] release_sysfs_dirent sysfs_dirent use after free:
>>> ptysb-uevent
>>
>> Sasha, thanks for your test.
>>
>> So is the oops always triggered on this node of 'ptysb-uevent' or the node
>> name
>> is changed every time?
>
> Also, we may dump stack on the release path with the below patch to see who
> did the ugly free.
>
> --
> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> index 2fbdff6..993671d 100644
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -281,6 +281,12 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
> */
> parent_sd = sd->s_parent;
>
> + if(!(sd->s_flags & SYSFS_FLAG_REMOVED)) {
> + printk("%s sysfs_dirent use after free: %s-%s\n",
> + __func__, parent_sd->s_name, sd->s_name);
> + dump_stack();
> + }
> +
> if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
> sysfs_put(sd->s_symlink.target_sd);
> if (sysfs_type(sd) & SYSFS_COPY_NAME)
> @@ -962,6 +968,9 @@ static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
> int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
> pos->s_parent == parent_sd &&
> hash == pos->s_hash;
> + if (valid && (atomic_read(&pos->s_count) <= 1))
> + printk("%s sysfs_dirent use after free: %s-%s\n",
> + __func__, parent_sd->s_name, pos->s_name);
> sysfs_put(pos);
> if (!valid)
> pos = NULL;
>
I don't think it shows what we want it to show thought:
[ 327.416905] Pid: 10504, comm: trinity-child98 Tainted: G W
3.9.0-rc2-next-20130315-sasha-00046-gecde602-dirty #301
[ 327.418815] Call Trace:
[ 327.419255] [<ffffffff812f880e>] release_sysfs_dirent+0x4e/0x120
[ 327.420595] [<ffffffff812f89d2>] sysfs_dir_pos+0x92/0x130
[ 327.421608] [<ffffffff812f8b8d>] sysfs_readdir+0x11d/0x280
[ 327.422562] [<ffffffff8128b070>] ? SyS_ioctl+0xa0/0xa0
[ 327.423441] [<ffffffff8128b070>] ? SyS_ioctl+0xa0/0xa0
[ 327.424314] [<ffffffff8128b3e8>] vfs_readdir+0x78/0xc0
[ 327.425263] [<ffffffff8128b54c>] SyS_getdents+0x8c/0x110
[ 327.426173] [<ffffffff83d919d8>] tracesys+0xe1/0xe6
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