From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: P J P <ppandit@redhat.com>
Cc: Fam Zheng <fam@euphon.net>, Marcelo Tosatti <mtosatti@redhat.com>,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
QEMU Developers <qemu-devel@nongnu.org>,
Bugs SysSec <bugs-syssec@rub.de>,
Paolo Bonzini <pbonzini@redhat.com>,
Stefano Garzarella <sgarzare@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v3 1/2] scsi: lsi: exit infinite loop while executing script (CVE-2019-12068)
Date: Tue, 13 Aug 2019 12:31:44 +0200 [thread overview]
Message-ID: <b2944559-264e-cb48-8a04-4f238197f835@redhat.com> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1908131534020.10397@xnncv>
Hi Prasad,
On 8/13/19 12:05 PM, P J P wrote:
> +-- On Fri, 9 Aug 2019, P J P wrote --+
> | From: Prasad J Pandit <pjp@fedoraproject.org>
> |
> | When executing script in lsi_execute_script(), the LSI scsi
> | adapter emulator advances 's->dsp' index to read next opcode.
> | This can lead to an infinite loop if the next opcode is empty.
> | Exit such loop after reading 10k empty opcodes.
> |
> | Reported-by: Bugs SysSec <bugs-syssec@rub.de>
> | Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> | ---
> | hw/scsi/lsi53c895a.c | 11 ++++++++++-
> | 1 file changed, 10 insertions(+), 1 deletion(-)
> |
> | Update v3: raise an illegal instruction interrupt and exit
> | -> https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg01427.html
> |
> | diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
> | index 10468c1ec1..e703ef4c9d 100644
> | --- a/hw/scsi/lsi53c895a.c
> | +++ b/hw/scsi/lsi53c895a.c
> | @@ -185,6 +185,9 @@ static const char *names[] = {
> | /* Flag set if this is a tagged command. */
> | #define LSI_TAG_VALID (1 << 16)
> |
> | +/* Maximum instructions to process. */
> | +#define LSI_MAX_INSN 10000
> | +
> | typedef struct lsi_request {
> | SCSIRequest *req;
> | uint32_t tag;
> | @@ -1132,7 +1135,13 @@ static void lsi_execute_script(LSIState *s)
> |
> | s->istat1 |= LSI_ISTAT1_SRUN;
> | again:
> | - insn_processed++;
> | + if (++insn_processed > LSI_MAX_INSN) {
> | + trace_lsi_execute_script_tc_illegal();
> | + lsi_script_dma_interrupt(s, LSI_DSTAT_IID);
> | + lsi_disconnect(s);
> | + trace_lsi_execute_script_stop();
> | + return;
My understanding of Marcelo's explanation
(https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg01427.html) is
we can kill insn_processed.
> | + }
> | insn = read_dword(s, s->dsp);
> | if (!insn) {
> | /* If we receive an empty opcode increment the DSP by 4 bytes
> |
>
> Ping...?!
> --
> Prasad J Pandit / Red Hat Product Security Team
> 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
>
next prev parent reply other threads:[~2019-08-13 10:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 6:38 [Qemu-devel] [PATCH v3 0/2] scsi: lsi: break infinite loop after 10k instructions P J P
2019-08-09 6:38 ` [Qemu-devel] [PATCH v3 1/2] scsi: lsi: exit infinite loop while executing script (CVE-2019-12068) P J P
2019-08-13 10:05 ` P J P
2019-08-13 10:31 ` Philippe Mathieu-Daudé [this message]
2019-08-13 14:33 ` Paolo Bonzini
2019-08-14 10:25 ` P J P
2019-08-14 10:38 ` Paolo Bonzini
2019-08-14 12:08 ` P J P
2019-08-09 6:38 ` [Qemu-devel] [PATCH v3 2/2] scsi: lsi: use macro LSI_MAX_INSN instead of a magic number P J P
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=b2944559-264e-cb48-8a04-4f238197f835@redhat.com \
--to=philmd@redhat.com \
--cc=bugs-syssec@rub.de \
--cc=fam@euphon.net \
--cc=mark.cave-ayland@ilande.co.uk \
--cc=mtosatti@redhat.com \
--cc=pbonzini@redhat.com \
--cc=ppandit@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=sgarzare@redhat.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).