Messages in this thread | | | Date | Thu, 29 Nov 2012 11:08:18 +0900 | Subject | Re: [PATCH] zram: Prevent use of unmapped buffer | From | Minchan Kim <> |
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On Thu, Nov 29, 2012 at 10:45 AM, Nitin Gupta <ngupta@vflare.org> wrote: > On 11/28/2012 05:33 PM, Minchan Kim wrote: >> >> On Wed, Nov 28, 2012 at 02:15:05PM +0900, Minchan Kim wrote: >>> >>> Hi Nitin, >>> >>> On Mon, Nov 26, 2012 at 11:26:07PM -0800, Nitin Gupta wrote: >>>> >>>> The commit c8f2f0db1 ("zram: Fix handling of incompressible pages") >>>> introduced a bug which caused a kunmap()'ed buffer to be used in case >>> >>> I got confused by the descripton. :( >>> The descripton is not right. >>> The problem is to access freed memory, not accessing to kunmaped buffer. >>> >>> partial I/O write. >>> >>> 1. uncmem = kmalloc >>> 2. zram_decompress_page(uncmem) >>> 3. memcpy(uncmem, user_mem) >>> 4. lzo1x_1_compress(uncmem) >>> 5. kfree(uncmem) >>> 6. src = uncmem >>> 7. memcpy(cmem, src, clen) <----- HIT >>> >>>> of partial writes where the data was found to be incompressible. >>>> >> I got it. You shouldn't mention partial write for proper description >> because it was usecase for swap-over-zram so it can't make partial write. >> Without partial write mention, your description is right but the problem >> I mentioned above is another problem for partial write so we need a >> another >> patch. I will cook. > > > I will include explanation of both the cases: use of unmapped buffer > and freed buffer, when I resend these patches. >
As you know, I am going to solve lockdep problem and disksize setting problem. Apparently, it conflict with your diet series. So I would like to order our patches following as.
1. bug fix patch of unmapped/freed buffer - Nitin 2. diet patch based on 1 - Nitin 3. disksize setting and lockdep problem - Minchan
I will wait your two patchsets. If you have some trouble to hold the time to make the patch, please tell me. I will send 1 and 3 ahead so you can send 2 based on it.
-- Kind regards, Minchan Kim
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