Messages in this thread | | | Date | Thu, 19 Aug 2004 21:55:21 +0200 | From | Kurt Garloff <> | Subject | Re: [PATCH] bio_uncopy_user mem leak |
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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 :-(
Regards, -- Kurt Garloff, Director SUSE Labs, Novell Inc. [unhandled content-type:application/pgp-signature] | |