diff options
Diffstat (limited to 'results/classifier/gemma3:12b/kvm/810')
| -rw-r--r-- | results/classifier/gemma3:12b/kvm/810 | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/results/classifier/gemma3:12b/kvm/810 b/results/classifier/gemma3:12b/kvm/810 new file mode 100644 index 00000000..c589dcdf --- /dev/null +++ b/results/classifier/gemma3:12b/kvm/810 @@ -0,0 +1,72 @@ + +i386/sev: Crash in pc_system_parse_ovmf_flash caused by bad firmware file +Description of problem: +A specially-crafted flash file can cause the `memcpy()` call in +`pc_system_parse_ovmf_flash` (`hw/i386/pc_sysfw_ovmf.c`) to READ out-of-bounds +memory, because there's no check on the `tot_len` field which is read +from the flash file. In such case, `ptr - tot_len` will point to a +memory location *below* `flash_ptr` (hence the out-of-bounds read). + +This path is only taken when SEV is enabled (which requires +KVM and x86_64). +Steps to reproduce: +1. Create `bad_ovmf.fd` using the following python script: + ``` + from uuid import UUID + OVMF_TABLE_FOOTER_GUID = "96b582de-1fb2-45f7-baea-a366c55a082d" + b = bytearray(4096) + b[4046:4048] = b'\xff\xff' # tot_len field + b[4048:4064] = UUID("{" + OVMF_TABLE_FOOTER_GUID + "}").bytes_le + with open("bad_ovmf.fd", "wb") as f: + f.write(b) + ``` +2. Build QEMU with `--enable-sanitizers` +3. Start QEMU with SEV and the bad flash file: + ``` + qemu-system-x86_64 -enable-kvm -cpu host -machine q35 \ + -drive if=pflash,format=raw,unit=0,file=bad_ovmf.fd,readonly=on \ + -machine confidential-guest-support=sev0 \ + -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1,policy=0x0 + ``` +4. QEMU crashes with: `SUMMARY: AddressSanitizer: stack-buffer-underflow` +Additional information: +Crash example: + +``` +$ sudo build/qemu-system-x86_64 -enable-kvm -cpu host -machine q35 \ + -drive if=pflash,format=raw,unit=0,file=bad_ovmf.fd,readonly=on \ + -machine confidential-guest-support=sev0 \ + -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1,policy=0x0 +==523314==WARNING: ASan doesn't fully support makecontext/swapcontext functions and may produce false positives in some cases! +================================================================= +==523314==ERROR: AddressSanitizer: stack-buffer-underflow on address 0x7f05305fb180 at pc 0x7f0548d89480 bp 0x7ffed44a1980 sp 0x7ffed44a1128 +READ of size 65517 at 0x7f05305fb180 thread T0 + #0 0x7f0548d8947f (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x9b47f) + #1 0x556127c3331e in memcpy /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34 + #2 0x556127c3331e in pc_system_parse_ovmf_flash ../hw/i386/pc_sysfw_ovmf.c:82 + #3 0x556127c21a0c in pc_system_flash_map ../hw/i386/pc_sysfw.c:203 + #4 0x556127c21a0c in pc_system_firmware_init ../hw/i386/pc_sysfw.c:258 + #5 0x556127c1ddd9 in pc_memory_init ../hw/i386/pc.c:902 + #6 0x556127bdc387 in pc_q35_init ../hw/i386/pc_q35.c:207 + #7 0x5561273bfdd6 in machine_run_board_init ../hw/core/machine.c:1181 + #8 0x556127f77de1 in qemu_init_board ../softmmu/vl.c:2652 + #9 0x556127f77de1 in qmp_x_exit_preconfig ../softmmu/vl.c:2740 + #10 0x556127f7f24d in qemu_init ../softmmu/vl.c:3775 + #11 0x556126f947ac in main ../softmmu/main.c:49 + #12 0x7f05470e80b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2) + #13 0x556126fa639d in _start (/home/dmurik/git/qemu/build/qemu-system-x86_64+0x2a5739d) + +Address 0x7f05305fb180 is located in stack of thread T3 at offset 0 in frame + #0 0x556128a96f1f in qemu_sem_timedwait ../util/qemu-thread-posix.c:293 + + + This frame has 1 object(s): + [32, 48) 'ts' (line 295) <== Memory access at offset 0 partially underflows this variable +HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork + (longjmp and C++ exceptions *are* supported) +Thread T3 created by T0 here: + #0 0x7f0548d28805 in pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3a805) + #1 0x556128a97ecf in qemu_thread_create ../util/qemu-thread-posix.c:596 + +SUMMARY: AddressSanitizer: stack-buffer-underflow (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x9b47f) +``` |