Re: [PATCH 0/2] use unsigned type for MegasasState fields

[P J P]

  Hello Alex,

+-- On Tue, 12 May 2020, Alexander Bulekov wrote --+
| I noticed this since I found a similar issue recently, using a fuzzer. I 
| applied your patches, but I can still reproduce the heap-overflow, unless 
| I'm missing something:

Strange, because with uint16_t type, 'reply_queue_head' should not turn 
negative.

| cat << EOF | qemu-system-i386 -qtest stdio -nographic -monitor none \
| -serial none -M q35 -device megasas -device scsi-cd,drive=null0 \
| -blockdev driver=null-co,read-zeroes=on,node-name=null0 -nographic
| outl 0xcf8 0x80001814
| outl 0xcfc 0xc021
| outl 0xcf8 0x80001818
| outl 0xcf8 0x80001804
| outw 0xcfc 0x7
| outl 0xcf8 0x80001810
| outl 0xcfc 0xe10c0000
| outl 0xcf8 0x8000f810
| write 0x0 0x18 0x060017e1ff00f8ffffffff60efffffffffffffffffffffff
| write 0xff00 0x1 0x06
| write 0xc021e10c0040 0x81 
0x755e08ff0000845e08ff0000935e08ff0000a25e08ff0000b15e08ff0000c05e08ff0000cf5e08ff0000de5e08ff0000ed5e08ff0000fc5e08ff00000b5e08ff00001a5e08ff0000295e08ff0000385e08ff0000475e08ff0000565e08ff0000655e08ff0000745e08ff0000835e08ff0000925e08ff0000a15e08ff0000b05e08
| -M pc-q35-5.0 -no-shutdown -M q35 -device megasas -device scsi-cd,drive=null0 
-blockdev driver=null-co,read-zeroes=on,node-name=null0 -nographic
| EOF

Are qemu options just above EOF right?

This leads to an assert failure below

  qemu/qtest.c:546:qtest_process_command: assertion failed: (words[1] && 
words[2] && words[3])
  ...
  Aborted                 (core dumped) /tmp/im/bin/qemu-system-x86_64 -qtest 
  stdio -nographic -monitor none -serial none -M q35 -device megasas -device 
  scsi-cd,drive=null0 -blockdev driver=null-co,read-zeroes=on,node-name=null0 
-nographic < ins


Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D