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Assertion failure in fifo8_push_all() through am53c974
Hello,
Using hypervisor fuzzer, hyfuzz, I found an assertion failure through am53c974 emulator.
A malicious guest user/process could use this flaw to abort the QEMU process on the host, resulting in a denial of service.
This was found in version 5.2.0 (master, 3f8d1885e4)
```
qemu-system-i386: ../util/fifo8.c:43: fifo8_push_all: Assertion `fifo->num + num <= fifo->capacity' failed.
#0 0x00007ffff0218fb7 in __GI_raise (sig=sig@entry=0x6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007ffff021a921 in __GI_abort () at abort.c:79
#2 0x00007ffff020a48a in __assert_fail_base (fmt=0x7ffff0391750 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x555558ed2400 "fifo->num + num <= fifo->capacity", file=file@entry=0x555558ed2380 "../util/fifo8.c", line=line@entry=0x2b, function=function@entry=0x555558ed2560 <__PRETTY_FUNCTION__.16583> "fifo8_push_all")
at assert.c:92
#3 0x00007ffff020a502 in __GI___assert_fail (assertion=assertion@entry=0x555558ed2400 "fifo->num + num <= fifo->capacity", file=file@entry=0x555558ed2380 "../util/fifo8.c", line=line@entry=0x2b, function=function@entry=0x555558ed2560 <__PRETTY_FUNCTION__.16583> "fifo8_push_all") at assert.c:101
#4 0x00005555587749c4 in fifo8_push_all (fifo=fifo@entry=0x61f000005200, data=data@entry=0x7fff72bfa640 "", num=num@entry=0x24) at ../util/fifo8.c:43
#5 0x00005555572bd13e in esp_do_dma (s=s@entry=0x61f000005088) at ../hw/scsi/esp.c:577
#6 0x00005555572bfc8f in handle_ti (s=0x61f000005088) at ../hw/scsi/esp.c:845
#7 0x00005555572c419c in esp_reg_write (s=0x61f000005088, saddr=saddr@entry=0x3, val=<optimized out>)
at ../hw/scsi/esp.c:987
#8 0x0000555557bb916a in esp_pci_io_write (opaque=0x61f000004680, addr=<optimized out>, val=<optimized out>, size=<optimized out>) at ../hw/scsi/esp-pci.c:214
#9 0x000055555817ea28 in memory_region_write_accessor (mr=0x61f000004f70, addr=<optimized out>, value=<optimized out>, size=<optimized out>, shift=<optimized out>, mask=<optimized out>, attrs=...) at ../softmmu/memory.c:491
#10 0x0000555558176671 in access_with_adjusted_size (addr=addr@entry=0xc, value=value@entry=0x7fff72bfb2a8, size=size@entry=0x1, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=
0x55555817e7c0 <memory_region_write_accessor>, mr=0x61f000004f70, attrs=...) at ../softmmu/memory.c:552
#11 0x00005555581892aa in memory_region_dispatch_write (mr=mr@entry=0x61f000004f70, addr=<optimized out>, data=<optimized out>, data@entry=0xffffff90, op=op@entry=MO_8, attrs=..., attrs@entry=...) at ../softmmu/memory.c:1508
#12 0x0000555558024b66 in address_space_stb (as=<optimized out>, addr=<optimized out>, val=<optimized out>, attrs=..., result=0x0) at /home/cwmyung/prj/hyfuzz/src/qemu-master/memory_ldst.c.inc:382
#13 0x00007fff9323641c in code_gen_buffer ()
#14 0x0000555557e793bb in cpu_tb_exec (tb_exit=<optimized out>, itb=<optimized out>, cpu=0x62e0000004b4)
at ../accel/tcg/cpu-exec.c:190
#15 0x0000555557e793bb in cpu_loop_exec_tb (tb_exit=<optimized out>, last_tb=<optimized out>, tb=<optimized out>, cpu=0x62e0000004b4) at ../accel/tcg/cpu-exec.c:673
#16 0x0000555557e793bb in cpu_exec (cpu=cpu@entry=0x62e000000400) at ../accel/tcg/cpu-exec.c:798
#17 0x0000555557f5fc5a in tcg_cpus_exec (cpu=cpu@entry=0x62e000000400) at ../accel/tcg/tcg-accel-ops.c:68
#18 0x00005555582260af in mttcg_cpu_thread_fn (arg=arg@entry=0x62e000000400) at ../accel/tcg/tcg-accel-ops-mttcg.c:70
#19 0x0000555558777b05 in qemu_thread_start (args=<optimized out>) at ../util/qemu-thread-posix.c:521
#20 0x00007ffff05d26db in start_thread (arg=0x7fff72bff700) at pthread_create.c:463
#21 0x00007ffff02fb71f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
```
To reproduce the assertion failure, please run the QEMU with the following command line.
```
$ ./qemu-system-i386 -m 512 -drive file=./hyfuzz.img,index=0,media=disk,format=raw -device am53c974,id=scsi -device scsi-hd,drive=SysDisk -drive id=SysDisk,if=none,file=./disk.img
```
Please let me know if I can provide any further info.
Thank you.
- Cheolwoo, Myung (Seoul National University)
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