Messages in this thread | | | Date | Wed, 28 Nov 2012 14:15:05 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH] zram: Prevent use of unmapped buffer |
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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. > > This fixes bug 50081: > https://bugzilla.kernel.org/show_bug.cgi?id=50081 > > Signed-off-by: Nitin Gupta <ngupta@vflare.org> > Reported-by: Mihail Kasadjikov <hamer.mk@gmail.com> > Reported-by: Tomas M <tomas@slax.org>
Good catch! Shame on me. I should have reivewed more carefully. :( Please resend it with revised descrption and title. I will rebase mh patchset just sent on top of this bug fix patch.
P.S) Sigh, Now code isn't clean due to partial read/write path handling. IMHO, sooner or later, we need refactoring.
-- Kind regards, Minchan Kim
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