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SubjectRe: [PATCH] bio_uncopy_user mem leak
Kurt Garloff wrote:
> Hi Chris,
>
> On Thu, Aug 19, 2004 at 09:51:34AM -0400, Chris Mason wrote:
>
>>On Thu, 2004-08-19 at 07:07, Con Kolivas wrote:
>>
>>>Ok I just tested this patch discretely and indeed the memory leak goes
>>>away but it still produces coasters so something is still amuck. Just as
>>>a data point; burning DVDs and data cds is ok. Burning audio *and
>>>videocds* is not.
>>
>>It might be the cold medicine talking, but I think we need something
>>like this. gcc tested it for me, beyond that I make no promises....
>>
>>--- l/fs/bio.c.1 2004-08-19 09:36:13.596858736 -0400
>>+++ l/fs/bio.c 2004-08-19 09:47:46.392537784 -0400
>>@@ -454,6 +454,7 @@
>> */
>> if (!ret) {
>> if (!write_to_vm) {
>>+ unsigned long p = uaddr;
>> bio->bi_rw |= (1 << BIO_RW);
>> /*
>> * for a write, copy in data to kernel pages
>>@@ -462,8 +463,9 @@
>> bio_for_each_segment(bvec, bio, i) {
>> char *addr = page_address(bvec->bv_page);
>>
>>- if (copy_from_user(addr, (char *) uaddr, bvec->bv_len))
>>+ if (copy_from_user(addr, (char *) p, bvec->bv_len))
>> goto cleanup;
>>+ p += bvec->bv_len;
>> }
>> }
>>
>
>
> Hmm, that patch would make a lot of sense to me.
>
> It matches the problem description; burning data CDs, we don't
> use bounce buffers, so that does not use this code path. Here,
> it looks like we copied the same userspace page again and again
> into a multisegment BIO. Ouch!
>
> Not yet tested either :-(

Ok looks like your cold medicine is working well for you ;-). This patch
on top of the other patch has the memory freeing _and_ burns good cds.
Well done. I only tested with a video cd. Can someone confirm audio cd
(although it seems obvious it would help both).

Andrew did you threaten to make a 2.6.8.2 since 2.6.8{,.1} cannot safely
burn an audio cd?

Cheers,
Con
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