Hi,
On Wed, Dec 07, 2016 at 01:22:00AM +0100, Christian Groessler wrote:
> Hi,
>
> the attached patch prevents a crash when trying to mount a corrupted ext4
> file system.
Why isn't it a backport of the equivalent mainline commit ? Is mainline
not affected by the same bug ? Unless this is the case (and the mainline
commit which made this one unnecessary) all fixes must go to mainline
first before being backported to stable.
> regards,
> chris
>
Thanks,
Willy
---
> >From 86344aebe7e3905b2293a7891a68def8cb38a571 Mon Sep 17 00:00:00 2001
> From: Christian Groessler <chris@xxxxxxxxxxxxx>
> Date: Wed, 7 Dec 2016 00:54:03 +0100
> Subject: [PATCH] Fix kernel crash when trying to mount corrupted ext4
> partition.
>
> ext4_calculate_overhead(), if successful, sets the 'ret' vatiable to 0.
> Subsequent failures will bail out, with the function returning the 'ret'
> variable as status. Since 'ret' is 0 (indicating no error) the kernel
> will happily continue and eventually crash.
>
> This change preserves the value of 'ret' across the call to
> ext4_calculate_overhead() in case this function doesn't return an
> error.
>
> Signed-off-by: Christian Groessler <chris@xxxxxxxxxxxxx>
> ---
> fs/ext4/super.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 5862518..0f63644 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3692,9 +3692,12 @@ no_journal:
> if (es->s_overhead_clusters)
> sbi->s_overhead = le32_to_cpu(es->s_overhead_clusters);
> else {
> + int oret = ret;
> ret = ext4_calculate_overhead(sb);
> if (ret)
> goto failed_mount_wq;
> + else
> + ret = oret;
> }
>
> /*
> --
> 2.7.4
>
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