Re: [PATCH] procfs: Fix error handling of proc_register()

[Nicolas Dichtel <nicolas.dichtel@6wind.com>]

Le 23/10/2014 00:40, Andrew Morton a écrit :
> On Thu, 16 Oct 2014 16:46:02 -0400 Debabrata Banerjee <dbanerje@akamai.com> wrote:
>
>> 	I don't see why this should print warnings at all instead of properly
>> 	unrolling allocations and returning an appropriate error. It's actually
>> 	leaking resources currently.
>
> I think the warnings are useful - a duplicate name in /proc is a
> significant kernel bug and we'll want to know precisely what caused it
> and get it fixed up quickly.  So let's keep that bit.
>
>> --- a/fs/proc/generic.c
>> +++ b/fs/proc/generic.c
>> @@ -304,6 +304,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
>>   		dp->proc_iops = &proc_file_inode_operations;
>>   	} else {
>>   		WARN_ON(1);
>> +		proc_free_inum(dp->low_ino);
>>   		return -EINVAL;
>>   	}
>>
>> @@ -311,9 +312,13 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
>>
>>   	for (tmp = dir->subdir; tmp; tmp = tmp->next)
>>   		if (strcmp(tmp->name, dp->name) == 0) {
>> -			WARN(1, "proc_dir_entry '%s/%s' already registered\n",
>> -				dir->name, dp->name);
>> -			break;
>> +			spin_unlock(&proc_subdir_lock);
>> +
>> +			if (S_ISDIR(dp->mode))
>> +				dir->nlink--;
>> +
>> +			proc_free_inum(dp->low_ino);
>> +			return -EEXIST;
>>   		}
>
> Your patch conflicts somewhat with Nicolas's "fs/proc: use a rb tree for
> the directory entries".  Here's what I ended up with:
>
>
>
> From: Debabrata Banerjee <dbanerje@akamai.com>
> Subject: procfs: fix error handling of proc_register()
>
> proc_register() error paths are leaking inodes and directory refcounts.
>
> Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
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