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Subject: Re: mount on tmpfs failing to parse context option
To:     Al Viro <viro@zeniv.linux.org.uk>, Hugh Dickins <hughd@google.com>
Cc:     David Howells <dhowells@redhat.com>, Linux-MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org
References: <d5b67332-57b7-c19a-0462-f84d07ef1a16@redhat.com>
 <d7f83334-d731-b892-ee49-1065d64a4887@redhat.com>
 <alpine.LSU.2.11.1910071655060.4431@eggly.anvils>
 <20191008012622.GP26530@ZenIV.linux.org.uk>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <9349bbbe-31fe-2b0a-001d-2e22ee20c12f@redhat.com>
Date:   Tue, 8 Oct 2019 12:33:15 -0400
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On 10/7/19 9:26 PM, Al Viro wrote:
> On Mon, Oct 07, 2019 at 05:50:31PM -0700, Hugh Dickins wrote:
> 
> [sorry for being MIA - had been sick through the last week, just digging
> myself from under piles of mail; my apologies]
> 
>> (tmpfs, very tiresomely, supports a NUMA "mpol" mount option which can
>> have commas in it e.g "mpol=bind:0,2": which makes all its comma parsing
>> awkward.  I assume that where the new mount API commits bend over to
>> accommodate that peculiarity, they end up mishandling the comma in
>> the context string above.)
> 
> 	Dumber than that, I'm afraid.  mpol is the reason for having
> ->parse_monolithic() in the first place, all right, but the problem is
> simply the lack of security_sb_eat_lsm_opts() call in it.
> 
> 	Could you check if the following fixes that one?
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 0f7fd4a85db6..8dcc8d04cbaf 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -3482,6 +3482,12 @@ static int shmem_parse_options(struct fs_context *fc, void *data)
>   {
>   	char *options = data;
>   
> +	if (options) {
> +		int err = security_sb_eat_lsm_opts(options, &fc->security);
> +		if (err)
> +			return err;
> +	}
> +
>   	while (options != NULL) {
>   		char *this_char = options;
>   		for (;;) {
> 

Yes the reporter says that works.

Thanks,
Laura