On 210906 2019, Philippe Mathieu-Daudé wrote: > (Forgot to Cc Alex for eventual reproducer)
Here you go. Should we be fuzzing this on OSS-Fuzz? ============= 8< ============= /* * cat << EOF | ./qemu-system-i386 -display none -machine accel=qtest, -m \ * 512M -device ati-vga,romfile= -nodefaults -qtest /dev/null -qtest stdio * outl 0xcf8 0x80001018 * outl 0xcfc 0xe1000000 * outl 0xcf8 0x80001004 * outw 0xcfc 0x02 * write 0xe10016c4 0x1 0x04 * write 0xe10016e4 0x1 0x58 * write 0xe1001438 0x4 0x0400001a * write 0xe100143c 0x4 0x01000015 * EOF */ static void test_fuzz(void) { QTestState *s = qtest_init( "-display none , -m 512M -device ati-vga,romfile= -nodefaults -qtest /dev/null"); qtest_outl(s, 0xcf8, 0x80001018); qtest_outl(s, 0xcfc, 0xe1000000); qtest_outl(s, 0xcf8, 0x80001004); qtest_outw(s, 0xcfc, 0x02); qtest_bufwrite(s, 0xe10016c4, "\x04", 0x1); qtest_bufwrite(s, 0xe10016e4, "\x58", 0x1); qtest_bufwrite(s, 0xe1001438, "\x04\x00\x00\x1a", 0x4); qtest_bufwrite(s, 0xe100143c, "\x01\x00\x00\x15", 0x4); qtest_quit(s); } ============= >8 ============= -Alex > > On 9/6/21 6:44 PM, Mauro Matteo Cascella wrote: > > On Mon, Sep 6, 2021 at 5:31 PM Philippe Mathieu-Daudé <phi...@redhat.com> > > wrote: > >> > >> When building QEMU with DEBUG_ATI defined then running with > >> '-device ati-vga,romfile="" -d unimp,guest_errors -trace ati\*' > >> we get: > >> > >> ati_mm_write 4 0x16c0 DP_CNTL <- 0x1 > >> ati_mm_write 4 0x146c DP_GUI_MASTER_CNTL <- 0x2 > >> ati_mm_write 4 0x16c8 DP_MIX <- 0xff0000 > >> ati_mm_write 4 0x16c4 DP_DATATYPE <- 0x2 > >> ati_mm_write 4 0x224 CRTC_OFFSET <- 0x0 > >> ati_mm_write 4 0x142c DST_PITCH_OFFSET <- 0xfe00000 > >> ati_mm_write 4 0x1420 DST_Y <- 0x3fff > >> ati_mm_write 4 0x1410 DST_HEIGHT <- 0x3fff > >> ati_mm_write 4 0x1588 DST_WIDTH_X <- 0x3fff3fff > >> ati_2d_blt: vram:0x7fff5fa00000 addr:0 ds:0x7fff61273800 stride:2560 > >> bpp:32 rop:0xff > >> ati_2d_blt: 0 0 0, 0 127 0, (0,0) -> (16383,16383) 16383x16383 > ^ > >> ati_2d_blt: pixman_fill(dst:0x7fff5fa00000, stride:254, bpp:8, x:16383, > >> y:16383, w:16383, h:16383, xor:0xff000000) > >> Thread 3 "qemu-system-i38" received signal SIGSEGV, Segmentation fault. > >> (gdb) bt > >> #0 0x00007ffff7f62ce0 in sse2_fill.lto_priv () at > >> /lib64/libpixman-1.so.0 > >> #1 0x00007ffff7f09278 in pixman_fill () at /lib64/libpixman-1.so.0 > >> #2 0x0000555557b5a9af in ati_2d_blt (s=0x631000028800) at > >> hw/display/ati_2d.c:196 > >> #3 0x0000555557b4b5a2 in ati_mm_write (opaque=0x631000028800, > >> addr=5512, data=1073692671, size=4) at hw/display/ati.c:843 > >> #4 0x0000555558b90ec4 in memory_region_write_accessor > >> (mr=0x631000039cc0, addr=5512, ..., size=4, ...) at softmmu/memory.c:492 > >> > >> Commit 584acf34cb0 ("ati-vga: Fix reverse bit blts") introduced > >> the local dst_x and dst_y which adjust the (x, y) coordinates > >> depending on the direction in the SRCCOPY ROP3 operation, but > >> forgot to address the same issue for the PATCOPY, BLACKNESS and > >> WHITENESS operations, which also call pixman_fill(). > >> > >> Fix that now by using the adjusted coordinates in the pixman_fill > >> call, and update the related debug printf(). > >> > >> Reported-by: Qiang Liu <qiang...@zju.edu.cn> > >> Fixes: 584acf34cb0 ("ati-vga: Fix reverse bit blts") > >> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> > >> --- > >> hw/display/ati_2d.c | 6 +++--- > >> 1 file changed, 3 insertions(+), 3 deletions(-) > >> > >> diff --git a/hw/display/ati_2d.c b/hw/display/ati_2d.c > >> index 4dc10ea7952..692bec91de4 100644 > >> --- a/hw/display/ati_2d.c > >> +++ b/hw/display/ati_2d.c > >> @@ -84,7 +84,7 @@ void ati_2d_blt(ATIVGAState *s) > >> DPRINTF("%d %d %d, %d %d %d, (%d,%d) -> (%d,%d) %dx%d %c %c\n", > >> s->regs.src_offset, s->regs.dst_offset, > >> s->regs.default_offset, > >> s->regs.src_pitch, s->regs.dst_pitch, s->regs.default_pitch, > >> - s->regs.src_x, s->regs.src_y, s->regs.dst_x, s->regs.dst_y, > >> + s->regs.src_x, s->regs.src_y, dst_x, dst_y, > >> s->regs.dst_width, s->regs.dst_height, > >> (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ? '>' : '<'), > >> (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ? 'v' : '^')); > >> @@ -180,11 +180,11 @@ void ati_2d_blt(ATIVGAState *s) > >> dst_stride /= sizeof(uint32_t); > >> DPRINTF("pixman_fill(%p, %d, %d, %d, %d, %d, %d, %x)\n", > >> dst_bits, dst_stride, bpp, > >> - s->regs.dst_x, s->regs.dst_y, > >> + dst_x, dst_y, > >> s->regs.dst_width, s->regs.dst_height, > >> filler); > >> pixman_fill((uint32_t *)dst_bits, dst_stride, bpp, > >> - s->regs.dst_x, s->regs.dst_y, > >> + dst_x, dst_y, > >> s->regs.dst_width, s->regs.dst_height, > >> filler); > >> if (dst_bits >= s->vga.vram_ptr + s->vga.vbe_start_addr && > >> -- > >> 2.31.1 > >> > > > > Tested-by: Mauro Matteo Cascella <mcasc...@redhat.com> > > Thanks. I wouldn't be surprise if we get another CVE in this code / > file / function ASAP this patch get merged... The code calls for a > rewrite, as per this function comment in its header: > > void ati_2d_blt(ATIVGAState *s) > { > /* FIXME it is probably more complex than this and may need to be */ > /* rewritten but for now as a start just to get some output: */ > > Regards, > > Phil. > >