zram: fix invalid memory references during disk write

Nitin Gupta ngupta at vflare.org
Tue Jan 15 00:48:18 UTC 2013


On Mon, Jan 14, 2013 at 11:19 AM, Greg KH <gregkh at linuxfoundation.org> wrote:
> On Wed, Dec 19, 2012 at 11:39:15AM -0600, Mitch Harder wrote:
>> On Wed, Dec 19, 2012 at 11:21 AM, Nitin Gupta <ngupta at vflare.org> wrote:
>> > On 12/19/2012 08:17 AM, Greg KH wrote:
>> >> On Wed, Dec 19, 2012 at 07:53:36AM -0800, Nitin Gupta wrote:
>> >>> On 12/19/2012 07:08 AM, Greg KH wrote:
>> >>>> On Tue, Dec 18, 2012 at 11:21:28PM -0800, Nitin Gupta wrote:
>> >>>>> On 12/18/2012 07:49 PM, Greg KH wrote:
>> >>>>>> On Tue, Dec 18, 2012 at 01:12:05PM -0800, Nitin Gupta wrote:
>> >>>>>>> On Tue, Dec 11, 2012 at 10:27 AM, Greg KH <gregkh at linuxfoundation.org> wrote:
>> >>>>>>>> On Thu, Nov 29, 2012 at 10:45:09PM -0800, Nitin Gupta wrote:
>> >>>>>>>>> Fixes a bug introduced by commit c8f2f0db1 ("zram: Fix handling
>> >>>>>>>>> of incompressible pages") which caused invalid memory references
>> >>>>>>>>> during disk write. Invalid references could occur in two cases:
>> >>>>>>>>>  - Incoming data expands on compression: In this case, reference was
>> >>>>>>>>> made to kunmap()'ed bio page.
>> >>>>>>>>>  - Partial (non PAGE_SIZE) write with incompressible data: In this
>> >>>>>>>>> case, reference was made to a kfree()'ed buffer.
>> >>>>>>>>>
>> >>>>>>>>> Fixes bug 50081:
>> >>>>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=50081
>> >>>>>>>>>
>> >>>>>>>>> Upstream commit ID: c8f2f0d: zram: Fix handling of incompressible pages
>> >>>>>>>>> Apply to versions: 3.6.5, 3.6.6, 3.6.7, 3.6.8
>> >>>>>>>>>
>> >>>>>>>>> Cc: <stable at vger.kernel.org> # staging-next: 37b51fd: zram: factor-out
>> >>>>>>>>>                               # zram_decompress_page() function
>> >>>>>>>>> Signed-off-by: Nitin Gupta <ngupta at vflare.org>
>> >>>>>>>>> Reported-by: Mihail Kasadjikov <hamer.mk at gmail.com>
>> >>>>>>>>> Reported-by: Tomas M <tomas at slax.org>
>> >>>>>>>>> Reviewed-by: Minchan Kim <minchan at kernel.org>
>> >>>>>>>>> ---
>> >>>>>>>>>  drivers/staging/zram/zram_drv.c |   39 ++++++++++++++++++++++++---------------
>> >>>>>>>>>  1 file changed, 24 insertions(+), 15 deletions(-)
>> >>>>>>>>
>> >>>>>>>> This patch fails to apply to 3.6.10:
>> >>>>>>>>
>> >>>>>>>> patching file drivers/staging/zram/zram_drv.c
>> >>>>>>>> Hunk #1 succeeded at 282 (offset 17 lines).
>> >>>>>>>> Hunk #2 FAILED at 286.
>> >>>>>>>> Hunk #3 succeeded at 319 (offset 17 lines).
>> >>>>>>>> Hunk #4 succeeded at 340 (offset 17 lines).
>> >>>>>>>> Hunk #5 succeeded at 353 (offset 17 lines).
>> >>>>>>>> Hunk #6 succeeded at 368 (offset 17 lines).
>> >>>>>>>> Hunk #7 succeeded at 385 (offset 17 lines).
>> >>>>>>>> 1 out of 7 hunks FAILED -- saving rejects to file drivers/staging/zram/zram_drv.c.rej
>> >>>>>>>>
>> >>>>>>>> Please redo this patch and resend it if you wish for it to be applied to
>> >>>>>>>> the 3.6-stable tree.
>> >>>>>>>>
>> >>>>>>>>
>> >>>>>>>
>> >>>>>>> Please apply this patch to stable tree asap.
>> >>>>>>
>> >>>>>> 3.6 is now end-of-life, there will not be any more releases for that
>> >>>>>> kernel series anymore, sorry.
>> >>>>>>
>> >>>>>
>> >>>>> Then please apply to 3.7.
>> >>>>
>> >>>> That is impossible to do so, for the obvious reason.
>> >>>>
>> >>>
>> >>> I meant to include it in whatever 3.7.x is released in future. Or put it
>> >>> in staging, so it may eventually make it to mainline (by 3.8?).
>> >>
>> >> {sigh}
>> >>
>> >> Please think for a moment for how it would be impossible for me to add
>> >> this patch to either the 3.7-stable tree, or the 3.8 tree, _again_.
>> >>
>> >
>> > I'm simply not getting it, I'm sorry, I must be missing something
>> > obvious -- what's really the problem with this: "whenever 3.8 is
>> > released, sometime in the future, just make sure that this fix is
>> > included in it" ?  Also, what's stopping it from staging, at least?
>> >
>>
>> Greg:
>>
>> I think there is still some residual confusion from the mix of patches
>> sent out for this issue.
>>
>> You appear to be saying that this patch as well as "37b51fd: zram:
>> factor-out  zram_decompress_page() function" have already been
>> applied.
>>
>> But I do not see either patch in 3.7.0 or in your message for
>> "3.7.1-stable review"
>>
>> I see the "37b51fd: zram: factor-out  zram_decompress_page() function"
>> patch in Linus' tree for 3.8_rc, but not the patch discussed in this
>> thread.
>
> Ok, I'm totally confused.
>
> Please, can someone tell me _exactly_ what commits they wish to see
> applied to the 3.7-stable tree.
>
> thanks,
>
> greg k-h

These two needs to be applied to 3.7-stable:

1) 37b51fd: "staging: zram: factor-out zram_decompress_page() function"

and then...

2) 397c606: "staging: zram: fix invalid memory references during disk write"


Thanks,
Nitin



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