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Date:   Fri, 6 Oct 2017 18:37:11 -0700
From:   Linus Torvalds <>
To:     Jia-Ju Bai <>
Cc:     Al Viro <>, Jan Kara <>,
        Sagi Grimberg <>,,
        "" <>,
        linux-fsdevel <>,
        Linux Kernel Mailing List <>
Subject: Re: [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in parse_options

On Fri, Oct 6, 2017 at 6:20 PM, Jia-Ju Bai <> wrote:
> To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
> This bug is found by my static analysis tool and my code review.

I'm not saying your patch is wrong, but it's a shame that we do that
extra allocation in match_number() and match_u64int(), and that we
don't have anything that is just size-limited.

And there really isn't anything saying that we shouldn't do the same
silly thing to match_u64int(). Maybe we don't have any actual users
that need it for now, but still..

Oh well.

I do wonder if we shouldn't just use something like

 "skip leading zeroes, copy to size-limited stack location instead"

because the input length really *is* limited once you skip leading
zeroes (and whatever base marker we have). We might have at most a
64-bit value in octal, so 22 bytes max.

But I guess just changing the two GFP_KERNEL's to GFP_ATOMIC is much simpler.


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