From: Paolo Bonzini <pbonzini@redhat.com>
To: Li Qiang <liq3ea@gmail.com>,
Bug 1886362 <1886362@bugs.launchpad.net>,
Jason Wang <jasowang@redhat.com>
Cc: Qemu Developers <qemu-devel@nongnu.org>
Subject: Re: [Bug 1886362] [NEW] Heap use-after-free in lduw_he_p through e1000e_write_to_rx_buffers
Date: Thu, 9 Jul 2020 19:36:53 +0200 [thread overview]
Message-ID: <2cbdf822-c74c-1af9-e5e6-7dd71412201e@redhat.com> (raw)
In-Reply-To: <CAKXe6S+J3nARveToQjECbwV224gs66WkqGHybUhfw35t1+V8og@mail.gmail.com>
On 09/07/20 17:51, Li Qiang wrote:
> Maybe we should check whether the address is a RAM address in 'dma_memory_rw'?
> But it is a hot path. I'm not sure it is right. Hope more discussion.
Half of the purpose of dma-helpers.c (as opposed to address_space_*
functions in exec.c) is exactly to support writes to MMIO. This is
especially true of dma_blk_io, which takes care of doing the DMA via a
bounce buffer, possibly in multiple steps and even blocking due to
cpu_register_map_client.
For dma_memory_rw this is not needed, so it only needs to handle
QEMUSGList, but I think the design should be the same.
However, this is indeed a nightmare for re-entrancy. The easiest
solution is to delay processing of descriptors to a bottom half whenever
MMIO is doing something complicated. This is also better for latency
because it will free the vCPU thread more quickly and leave the work to
the I/O thread.
Paolo
next prev parent reply other threads:[~2020-07-09 17:38 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 2:44 [Bug 1886362] [NEW] Heap use-after-free in lduw_he_p through e1000e_write_to_rx_buffers Alexander Bulekov
2020-07-07 4:52 ` [Bug 1886362] " Philippe Mathieu-Daudé
2020-07-09 15:51 ` [Bug 1886362] [NEW] " Li Qiang
2020-07-09 17:36 ` Paolo Bonzini [this message]
2020-07-10 10:37 ` Li Qiang
2020-07-14 8:56 ` Jason Wang
2020-07-14 8:56 ` Jason Wang
2020-07-14 10:48 ` Li Qiang
2020-07-15 8:35 ` Jason Wang
2020-07-15 8:35 ` Jason Wang
2020-07-21 12:31 ` Peter Maydell
2020-07-21 12:31 ` Peter Maydell
2020-07-21 13:21 ` Jason Wang
2020-07-21 13:21 ` Jason Wang
2020-07-21 13:44 ` Peter Maydell
2020-07-21 13:44 ` Peter Maydell
2020-07-21 14:37 ` Alexander Bulekov
2020-07-21 14:37 ` Alexander Bulekov
2020-07-22 3:25 ` Jason Wang
2020-07-22 3:25 ` Jason Wang
2020-07-21 13:46 ` Li Qiang
2020-07-22 3:27 ` Jason Wang
2020-07-22 3:27 ` Jason Wang
2020-07-21 12:14 ` [Bug 1886362] " P J P
2021-05-26 14:34 ` Thomas Huth
2021-06-14 23:40 ` Alexander Bulekov
2021-06-15 18:19 ` Thomas Huth
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2cbdf822-c74c-1af9-e5e6-7dd71412201e@redhat.com \
--to=pbonzini@redhat.com \
--cc=1886362@bugs.launchpad.net \
--cc=jasowang@redhat.com \
--cc=liq3ea@gmail.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.