qemu/nbd
Eric Blake 51ae4f8455 nbd/server: CVE-2017-15118 Stack smash on large export name
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.

CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
2017-11-28 06:58:01 -06:00
..
Makefile.objs nbd: Split nbd.c 2016-01-15 18:58:02 +01:00
client.c nbd/client: Don't hard-disconnect on ESHUTDOWN from server 2017-11-17 08:34:34 -06:00
common.c nbd: Expose constants and structs for structured read 2017-10-30 21:07:21 +01:00
nbd-internal.h nbd: Minimal structured read for client 2017-10-30 21:48:41 +01:00
server.c nbd/server: CVE-2017-15118 Stack smash on large export name 2017-11-28 06:58:01 -06:00
trace-events nbd/server: Fix structured read of length 0 2017-11-09 10:25:11 -06:00