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Created attachment 1098916[details]
full backtrace
Description of problem:
a prewhql driver [1] allows resize beyond video memory limits on XP (bug 1285460). When attempting to do that, spice-gtk segfaults: #0 0x00007ffff55590fe in lz_rgb16_decompress (encoder=encoder@entry=0x1100c20, out_buf=out_buf@entry=0x7fffb95c3210, size=size@entry=8179200) at lz_decompress_tmpl.c:305
[1] https://brewweb.devel.redhat.com/buildinfo?buildID=457801
Version-Release number of selected component (if applicable):
spice-gtk3-0.26-5.el7.x86_64
How reproducible:
always
Steps to Reproduce:
1. have a XP VM with default video memory settings (ram/vgamem/vram: 64/16/64 MB) and qxl driver from [1] installed
2. connect to the VM
3. change resolution from OS applet (right click Desktop -> Options) beyond 2560x1600 or 2048x2048
Actual results:
segfault occurs:
#0 0x00007ffff55590fe in lz_rgb16_decompress (encoder=encoder@entry=0x1100c20, out_buf=out_buf@entry=0x7fffb95c3210, size=size@entry=8179200) at lz_decompress_tmpl.c:305
#1 0x00007ffff5565990 in lz_decode (lz=0x1100c20, to_type=<optimized out>, buf=0x7fffb95c3210 <Address 0x7fffb95c3210 out of bounds>) at lz.c:684
#2 0x00007ffff5547a53 in canvas_get_lz (canvas=canvas@entry=0xbebcf0, image=image@entry=0xc450a4, want_original=want_original@entry=0, invers=0) at ../spice-common/common/canvas_base.c:821
#3 0x00007ffff5547d47 in canvas_get_image_internal (canvas=canvas@entry=0xbebcf0, image=0xc450a4, want_original=want_original@entry=0, real_get=real_get@entry=1) at ../spice-common/common/canvas_base.c:1110
#4 0x00007ffff554992d in canvas_draw_copy (want_original=0, image=<optimized out>, canvas=0xbebcf0) at ../spice-common/common/canvas_base.c:1285
#5 0x00007ffff554992d in canvas_draw_copy (spice_canvas=0xbebcf0, bbox=0xc45024, clip=<optimized out>, copy=0xc45048) at ../spice-common/common/canvas_base.c:2258
#6 0x00007ffff552da9a in display_handle_draw_copy (channel=0xa4fa60 [SpiceDisplayChannel], in=<optimized out>) at channel-display.c:1559
#7 0x00007ffff5524394 in spice_channel_recv_msg (channel=0xa4fa60 [SpiceDisplayChannel], msg_handler=0x7ffff5523c10 <spice_channel_handle_msg>, data=0x0) at spice-channel.c:1877
#8 0x00007ffff5524514 in spice_channel_iterate_read (channel=0xa4fa60 [SpiceDisplayChannel]) at spice-channel.c:2114
#9 0x00007ffff5525cd0 in spice_channel_coroutine (channel=0xa4fa60 [SpiceDisplayChannel]) at spice-channel.c:2152
#10 0x00007ffff5525cd0 in spice_channel_coroutine (data=0xa4fa60) at spice-channel.c:2429
#11 0x00007ffff554e7cb in coroutine_trampoline (cc=0xa4f110) at coroutine_ucontext.c:63
#12 0x00007ffff554e609 in continuation_trampoline (i0=<optimized out>, i1=<optimized out>) at continuation.c:55
#13 0x00007ffff3609110 in __start_context () at /lib64/libc.so.6
#14 0x0000000000a4f4d8 in ()
#15 0x0000000000000000 in ()
Expected results:
remote-viewer survives the condition and works normally after the guest reverts back to previous working resolution
Additional info:
low prio/sev because this bug is triggered by another bug (bug 1285460)
in canvas_base.c line 870 stride is computed right only for 32 bit:
stride = (n_comp_pixels / height) * 4;
this is causing memory corruption if top_down is false due to
if (!top_down) {
stride = -stride;
decomp_buf = src + stride * (height - 1);
I fixed replacing
stride = (n_comp_pixels / height) * 4;
with
stride = pixman_image_get_stride(lz_data->decode_data.out_surface);
stride = abs(stride);
note that I'm getting some glitches due to the fact that on pixman stride is always a multiple of 4 (but this is probably another issue).
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHBA-2016-2229.html