QEMU – NBD Server Long Export Name Stack Buffer Overflow

• Exploit Database
• 121 阅读

• 作者： Eric Blake
  日期： 2017-11-29
• 类别：

  • dos
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/43194/
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  Introduced in commit f37708f6b8 (2.10).The NBD spec says a client can request export names up to 4096 bytes in length, even though they should not expect success on names longer than 256.However, qemu hard-codes the limit of 256, and fails to filter out a client that probes for a longer name; the result is a stack smash that can potentially give an attacker arbitrary control over the qemu process.   The smash can be easily demonstrated with this client:   $ qemu-io f raw nbd://localhost:10809/$(printf %3000d 1 | tr ' ' a)   If the qemu NBD server binary (whether the standalone qemu-nbd, or the builtin server of QMP nbd-server-start) was compiled with -fstack-protector-strong, the ability to exploit the stack smash into arbitrary execution is a lot more difficult (but still theoretically possible to a determined attacker, perhaps in combination with other CVEs).Still, crashing a running qemu (and losing the VM) is bad enough, even if the attacker did not obtain full execution control.