On Fri, 15 May 2020, Launchpad Bug Tracker wrote: > You have been subscribed to a public bug by Philippe Mathieu-Daudé (philmd): > > Hello, > While fuzzing, I found inputs that trigger assertion failures in > ati_reg_read_offs/ati_reg_write_offs > > uint32_t extract32(uint32_t, int, int): Assertion `start >= 0 && length >> 0 && length <= 32 - start' failed > > #3 0x00007ffff6866092 in __GI___assert_fail (assertion=0x555556e760c0 <str> > "start >= 0 && length > 0 && length <= 32 - start", file=0x555556e76120 <str> > "/home/alxndr/Development/qemu/include/qemu/bitops.h", line=0x12c, > function=0x555556e76180 <__PRETTY_FUNCTION__.extract32> "uint32_t > extract32(uint32_t, int, int)") at assert.c:101 > #4 0x000055555653d8a7 in ati_mm_read (opaque=<optimized out>, addr=0x1a, > size=<optimized out>) at > /home/alxndr/Development/qemu/include/qemu/log-for-trace.h:29 > #5 0x000055555653c825 in ati_mm_read (opaque=<optimized out>, addr=0x4, > size=<optimized out>) at /home/alxndr/Development/qemu/hw/display/ati.c:289 > #6 0x000055555601446e in memory_region_read_accessor (mr=0x63100004dc20, > addr=<optimized out>, value=<optimized out>, size=<optimized out>, > shift=<optimized out>, mask=<optimized out>, attrs=...) at > /home/alxndr/Development/qemu/memory.c:434 > #7 0x0000555556001a70 in access_with_adjusted_size (addr=<optimized out>, > value=<optimized out>, size=<optimized out>, access_size_min=<optimized out>, > access_size_max=<optimized out>, access_fn=<optimized out>, > mr=0x63100004dc20, attrs=...) at /home/alxndr/Development/qemu/memory.c:544 > #8 0x0000555556001a70 in memory_region_dispatch_read1 (mr=0x63100004dc20, > addr=0x4, pval=<optimized out>, size=0x4, attrs=...) at > /home/alxndr/Development/qemu/memory.c:1396
Here's a stack trace with --enable debug which is more useful: #4 0x0000555555b39464 in extract32 (value=0, start=16, length=32) at /home/balaton/src/qemu/include/qemu/bitops.h:300 #5 0x0000555555b3a45f in ati_reg_read_offs (reg=0, offs=2, size=4) at hw/display/ati.c:269 #6 0x0000555555b3a9f1 in ati_mm_read (opaque=0x555556f35610, addr=26, size=4) at hw/display/ati.c:299 #7 0x0000555555b3a988 in ati_mm_read (opaque=0x555556f35610, addr=4, size=4) at hw/display/ati.c:290 It's trying to do an indexed read via MM_DATA reg of the middle of reg 0x18 BIOS_2_SCRATCH which ends up calling ati_reg_read_offs with out of bound values. Maybe we should clamp size somewhere. Regards, BALATON Zoltan -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1878134 Title: Assertion failures in ati_reg_read_offs/ati_reg_write_offs Status in QEMU: New Bug description: Hello, While fuzzing, I found inputs that trigger assertion failures in ati_reg_read_offs/ati_reg_write_offs uint32_t extract32(uint32_t, int, int): Assertion `start >= 0 && length > 0 && length <= 32 - start' failed #3 0x00007ffff6866092 in __GI___assert_fail (assertion=0x555556e760c0 <str> "start >= 0 && length > 0 && length <= 32 - start", file=0x555556e76120 <str> "/home/alxndr/Development/qemu/include/qemu/bitops.h", line=0x12c, function=0x555556e76180 <__PRETTY_FUNCTION__.extract32> "uint32_t extract32(uint32_t, int, int)") at assert.c:101 #4 0x000055555653d8a7 in ati_mm_read (opaque=<optimized out>, addr=0x1a, size=<optimized out>) at /home/alxndr/Development/qemu/include/qemu/log-for-trace.h:29 #5 0x000055555653c825 in ati_mm_read (opaque=<optimized out>, addr=0x4, size=<optimized out>) at /home/alxndr/Development/qemu/hw/display/ati.c:289 #6 0x000055555601446e in memory_region_read_accessor (mr=0x63100004dc20, addr=<optimized out>, value=<optimized out>, size=<optimized out>, shift=<optimized out>, mask=<optimized out>, attrs=...) at /home/alxndr/Development/qemu/memory.c:434 #7 0x0000555556001a70 in access_with_adjusted_size (addr=<optimized out>, value=<optimized out>, size=<optimized out>, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=<optimized out>, mr=0x63100004dc20, attrs=...) at /home/alxndr/Development/qemu/memory.c:544 #8 0x0000555556001a70 in memory_region_dispatch_read1 (mr=0x63100004dc20, addr=0x4, pval=<optimized out>, size=0x4, attrs=...) at /home/alxndr/Development/qemu/memory.c:1396 I can reproduce it in qemu 5.0 built with using: cat << EOF | ~/Development/qemu/build/i386-softmmu/qemu-system-i386 -M pc-q35-5.0 -device ati-vga -nographic -qtest stdio -monitor none -serial none outl 0xcf8 0x80001018 outl 0xcfc 0xe2000000 outl 0xcf8 0x8000101c outl 0xcf8 0x80001004 outw 0xcfc 0x7 outl 0xcf8 0x8000fa20 write 0xe2000004 0x1 0x1a readq 0xe2000000 EOF Similarly for ati_reg_write_offs: cat << EOF | ~/Development/qemu/build/i386-softmmu/qemu-system-i386 -M pc-q35-5.0 -device ati-vga -nographic -qtest stdio -monitor none -serial none outl 0xcf8 0x80001018 outl 0xcfc 0xe2000000 outl 0xcf8 0x8000101c outl 0xcf8 0x80001004 outw 0xcfc 0x7 outl 0xcf8 0x8000fa20 write 0xe2000000 0x8 0x6a00000000006a00 EOF I also attached the traces to this launchpad report, in case the formatting is broken: qemu-system-i386 -M pc-q35-5.0 -device ati-vga -nographic -qtest stdio -monitor none -serial none < attachment Please let me know if I can provide any further info. -Alex To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1878134/+subscriptions
