QEMU-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Alexander Bulekov <alxndr@bu.edu>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [RFC PATCH v2] hw/i386/vmport: Allow QTest use without crashing
Date: Sat, 23 May 2020 22:22:36 -0400
Message-ID: <20200524022230.rij2ehcmerhoj3ur@mozz.bu.edu> (raw)
In-Reply-To: <20200518103113.9882-1-f4bug@amsat.org>

On 200518 1231, Philippe Mathieu-Daudé wrote:
> Trying libFuzzer on the vmport device, we get:
> 
>   AddressSanitizer:DEADLYSIGNAL
>   =================================================================
>   ==29476==ERROR: AddressSanitizer: SEGV on unknown address 0x000000008840 (pc 0x56448bec4d79 bp 0x7ffeec9741b0 sp 0x7ffeec9740e0 T0)
>   ==29476==The signal is caused by a READ memory access.
>     #0 0x56448bec4d78 in vmport_ioport_read (qemu-fuzz-i386+0x1260d78)
>     #1 0x56448bb5f175 in memory_region_read_accessor (qemu-fuzz-i386+0xefb175)
>     #2 0x56448bb30c13 in access_with_adjusted_size (qemu-fuzz-i386+0xeccc13)
>     #3 0x56448bb2ea27 in memory_region_dispatch_read1 (qemu-fuzz-i386+0xecaa27)
>     #4 0x56448bb2e443 in memory_region_dispatch_read (qemu-fuzz-i386+0xeca443)
>     #5 0x56448b961ab1 in flatview_read_continue (qemu-fuzz-i386+0xcfdab1)
>     #6 0x56448b96336d in flatview_read (qemu-fuzz-i386+0xcff36d)
>     #7 0x56448b962ec4 in address_space_read_full (qemu-fuzz-i386+0xcfeec4)
> 
> X86CPU is NULL because QTest accelerator does not use CPU.
> Fix by returning default values when QTest accelerator is used.
> 

Ah - it was QTest. Thank you for this - I would always run into this
crash within a second of fuzzing.
-Alex


      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18 10:31 Philippe Mathieu-Daudé
2020-05-21 15:54 ` Paolo Bonzini
2020-05-24  2:22 ` Alexander Bulekov [this message]

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=20200524022230.rij2ehcmerhoj3ur@mozz.bu.edu \
    --to=alxndr@bu.edu \
    --cc=ehabkost@redhat.com \
    --cc=f4bug@amsat.org \
    --cc=mst@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=qemu-devel@nongnu.org \
    --cc=rth@twiddle.net \
    /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

QEMU-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/qemu-devel/0 qemu-devel/git/0.git
	git clone --mirror https://lore.kernel.org/qemu-devel/1 qemu-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 qemu-devel qemu-devel/ https://lore.kernel.org/qemu-devel \
		qemu-devel@nongnu.org
	public-inbox-index qemu-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.nongnu.qemu-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git