[Spice-devel] [PATCH 1/2 v3] remove dangling pointer for RedCharDeviceVDIPort
Frediano Ziglio
fziglio at redhat.com
Fri May 6 09:58:19 UTC 2016
>
> Hey,
>
> On Thu, May 05, 2016 at 05:03:58PM +0100, Frediano Ziglio wrote:
> > When a client disconnects remove it from the list of clients connected
> > to the spice char-device.
> >
> > This was caused by commit 1cec1c5118b65124de6bc6f984f376ff4e297bfb
> > ("reds: Make VDIPortState a GObject") as the lifespan of RedCharDevice
> > was changed.
> >
> > This could be reproduced with:
> > - start rhel7 machine
> > - connect remote viewer (RV)
> > - RV: login
> > - connect ssh
> > - SSH: stop agent
> > - disconnect RV
> > - SSH: start agent
> > - connect to RV
>
> Not sure if this is quite fixed yet. From latest upstream (with this patch),
> I
> can manage to crash the guest with:
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007fdfb4fed556 in vdi_port_read_one_msg_from_device (sin=0x5603d2a36c68,
> opaque=<optimized out>) at reds.c:840
> 840 g_assert(RED_CHAR_DEVICE(reds->agent_dev) == sin->st);
> (gdb) bt
> #0 0x00007fdfb4fed556 in vdi_port_read_one_msg_from_device
> (sin=0x5603d2a36c68, opaque=<optimized out>) at reds.c:840
> #1 0x00007fdfb4faad41 in red_char_device_read_from_device
> (dev=0x5603d2a3b150) at char-device.c:103
> #2 0x00007fdfb4faad41 in red_char_device_read_from_device
> (dev=0x5603d2a3b150) at char-device.c:347
> #3 0x00007fdfb4fad67c in red_char_device_start (dev=0x5603d2a3b150) at
> char-device.c:810
> #4 0x00007fdfb4fe9d38 in spice_server_vm_start (reds=0x5603d2af7300) at
> reds.c:4071
> #5 0x00005603cfc22a49 in qdev_reset_one ()
> #6 0x00005603cfc22358 in qbus_walk_children ()
> #7 0x00005603cfc22288 in qdev_walk_children ()
> #8 0x00005603cfc22358 in qbus_walk_children ()
> #9 0x00005603cfbb9a9a in qemu_system_reset ()
> #10 0x00005603cfaaf264 in main ()
>
> ...
>
> The agent restart also crashes the client which is what I'm focusing in fix
> at
> the moment... Happy crash Friday!
>
> Cheers,
> toso
>
Did you apply both patches? Looks like you encountered issue fixed by second one.
Are you able to easily reproduce it?
Even with v0.13.1 and this patch?
Frediano
> >
> > and caused (using address sanitizer):
> >
> > main_channel_handle_parsed: agent start
> > =================================================================
> > ==29592==ERROR: AddressSanitizer: heap-use-after-free on address
> > 0x60c00001cff0 at pc 0x7fa85b6e8595 bp 0x7ffde3801940 sp 0x7ffde3801930
> > READ of size 8 at 0x60c00001cff0 thread T0
> > #0 0x7fa85b6e8594 in red_client_get_main
> > /home/freddy/work/spice-server/server/red-channel.c:2190
> > #1 0x7fa85b7311e6 in vdi_port_send_msg_to_client
> > /home/freddy/work/spice-server/server/reds.c:880
> > #2 0x7fa85b69383e in red_char_device_send_msg_to_client
> > /home/freddy/work/spice-server/server/char-device.c:138
> > #3 0x7fa85b69383e in red_char_device_send_msg_to_clients
> > /home/freddy/work/spice-server/server/char-device.c:356
> > #4 0x7fa85b69383e in red_char_device_read_from_device
> > /home/freddy/work/spice-server/server/char-device.c:403
> > #5 0x55a2633b81c1 (/usr/bin/qemu-system-x86_64+0x5561c1)
> > #6 0x55a2633afe7a (/usr/bin/qemu-system-x86_64+0x54de7a)
> > #7 0x55a2634cb7b1 (/usr/bin/qemu-system-x86_64+0x6697b1)
> > #8 0x55a2632078d0 (/usr/bin/qemu-system-x86_64+0x3a58d0)
> > #9 0x55a26379b2e8 (/usr/bin/qemu-system-x86_64+0x9392e8)
> > #10 0x55a26379a7a0 (/usr/bin/qemu-system-x86_64+0x9387a0)
> > #11 0x55a26313fb78 in main (/usr/bin/qemu-system-x86_64+0x2ddb78)
> > #12 0x7fa85a3cc57f in __libc_start_main (/lib64/libc.so.6+0x2057f)
> > #13 0x55a26314b0c8 (/usr/bin/qemu-system-x86_64+0x2e90c8)
> >
> > 0x60c00001cff0 is located 48 bytes inside of 128-byte region
> > [0x60c00001cfc0,0x60c00001d040)
> > freed by thread T0 here:
> > #0 0x7fa869e3667a in __interceptor_free (/lib64/libasan.so.2+0x9867a)
> > #1 0x7fa85b6d75f7 in red_client_unref
> > /home/freddy/work/spice-server/server/red-channel.c:2076
> > #2 0x7fa85b6ead74 in dispatcher_handle_single_read
> > /home/freddy/work/spice-server/server/dispatcher.c:291
> > #3 0x7fa85b6ead74 in dispatcher_handle_recv_read
> > /home/freddy/work/spice-server/server/dispatcher.c:314
> > #4 0x55a26379b2e8 (/usr/bin/qemu-system-x86_64+0x9392e8)
> > #5 0x55a26379a7a0 (/usr/bin/qemu-system-x86_64+0x9387a0)
> > #6 0x55a26313fb78 in main (/usr/bin/qemu-system-x86_64+0x2ddb78)
> > #7 0x7fa85a3cc57f in __libc_start_main (/lib64/libc.so.6+0x2057f)
> >
> > previously allocated by thread T0 here:
> > #0 0x7fa869e36b19 in __interceptor_calloc (/lib64/libasan.so.2+0x98b19)
> > #1 0x7fa85b7d6858 in spice_malloc0
> > /home/freddy/work/spice-server/spice-common/common/mem.c:109
> > #2 0x7fa85b6e760c in red_client_new
> > /home/freddy/work/spice-server/server/red-channel.c:2053
> > #3 0x7fa85b7449e4 in reds_handle_main_link
> > /home/freddy/work/spice-server/server/reds.c:1762
> > #4 0x7fa85b7449e4 in reds_handle_link
> > /home/freddy/work/spice-server/server/reds.c:2002
> > #5 0x7fa85b745d3a in reds_handle_ticket
> > /home/freddy/work/spice-server/server/reds.c:2056
> > #6 0x55a26379b2e8 (/usr/bin/qemu-system-x86_64+0x9392e8)
> > #7 0x55a26379a7a0 (/usr/bin/qemu-system-x86_64+0x9387a0)
> > #8 0x55a26313fb78 in main (/usr/bin/qemu-system-x86_64+0x2ddb78)
> > #9 0x7fa85a3cc57f in __libc_start_main (/lib64/libc.so.6+0x2057f)
> >
> > SUMMARY: AddressSanitizer: heap-use-after-free
> > /home/freddy/work/spice-server/server/red-channel.c:2190
> > red_client_get_main
> > Shadow bytes around the buggy address:
> > 0x0c187fffb9a0: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
> > 0x0c187fffb9b0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
> > 0x0c187fffb9c0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
> > 0x0c187fffb9d0: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
> > 0x0c187fffb9e0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
> > =>0x0c187fffb9f0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd[fd]fd
> > 0x0c187fffba00: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
> > 0x0c187fffba10: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
> > 0x0c187fffba20: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
> > 0x0c187fffba30: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
> > 0x0c187fffba40: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
> >
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> > server/reds.c | 10 ++++------
> > 1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > Changes from v2:
> > - added a comment from Uri Lublin.
> >
> > diff --git a/server/reds.c b/server/reds.c
> > index efd1429..67c262a 100644
> > --- a/server/reds.c
> > +++ b/server/reds.c
> > @@ -603,12 +603,10 @@ void reds_client_disconnect(RedsState *reds,
> > RedClient *client)
> > reds_mig_remove_wait_disconnect_client(reds, client);
> > }
> >
> > - if (reds->agent_dev->priv->agent_attached) {
> > - /* note that vdagent might be NULL, if the vdagent was once
> > - * up and than was removed */
> > - if
> > (red_char_device_client_exists(RED_CHAR_DEVICE(reds->agent_dev), client))
> > {
> > -
> > red_char_device_client_remove(RED_CHAR_DEVICE(reds->agent_dev),
> > client);
> > - }
> > + /* note that client might be NULL, if the vdagent was once
> > + * up and than was removed */
> > + if (red_char_device_client_exists(RED_CHAR_DEVICE(reds->agent_dev),
> > client)) {
> > + red_char_device_client_remove(RED_CHAR_DEVICE(reds->agent_dev),
> > client);
> > }
> >
> > ring_remove(&client->link);
> > --
> > 2.5.5
> >
> > _______________________________________________
> > Spice-devel mailing list
> > Spice-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/spice-devel
>
More information about the Spice-devel
mailing list