gnu: qemu: Fix CVE-2017-{15118,15119}.

* gnu/packages/patches/qemu-CVE-2017-15118.patch,
gnu/packages/patches/qemu-CVE-2017-15119.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/virtualization.scm (qemu)[source]: Use them.

2 files changed, 126 insertions, 0 deletions

diff --git a/gnu/packages/patches/qemu-CVE-2017-15118.patch b/gnu/packages/patches/qemu-CVE-2017-15118.patch
new file mode 100644
index 0000000000..d427317be9
--- /dev/null
+++ b/gnu/packages/patches/qemu-CVE-2017-15118.patch
@@ -0,0 +1,58 @@
+Fix CVE-2017-15118:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15118
+https://bugzilla.redhat.com/show_bug.cgi?id=1516922
+
+Patch copied from upstream source repository:
+
+https://git.qemu.org/?p=qemu.git;a=commitdiff;h=51ae4f8455c9e32c54770c4ebc25bf86a8128183
+
+From 51ae4f8455c9e32c54770c4ebc25bf86a8128183 Mon Sep 17 00:00:00 2001
+From: Eric Blake <eblake@redhat.com>
+Date: Wed, 22 Nov 2017 15:07:22 -0600
+Subject: [PATCH] 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>
+---
+ nbd/server.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/nbd/server.c b/nbd/server.c
+index a81801e3bc..92c0fdd03b 100644
+--- a/nbd/server.c
++++ b/nbd/server.c
+@@ -386,6 +386,10 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,
+         msg = "name length is incorrect";
+         goto invalid;
+     }
++    if (namelen >= sizeof(name)) {
++        msg = "name too long for qemu";
++        goto invalid;
++    }
+     if (nbd_read(client->ioc, name, namelen, errp) < 0) {
+         return -EIO;
+     }
+-- 
+2.15.0
+
diff --git a/gnu/packages/patches/qemu-CVE-2017-15119.patch b/gnu/packages/patches/qemu-CVE-2017-15119.patch
new file mode 100644
index 0000000000..6265ecf8d6
--- /dev/null
+++ b/gnu/packages/patches/qemu-CVE-2017-15119.patch
@@ -0,0 +1,68 @@
+Fix CVE-2017-15119:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15119
+https://bugzilla.redhat.com/show_bug.cgi?id=1516925
+
+Patch copied from upstream source repository:
+
+https://git.qemu.org/?p=qemu.git;a=commitdiff;h=fdad35ef6c5839d50dfc14073364ac893afebc30
+
+From fdad35ef6c5839d50dfc14073364ac893afebc30 Mon Sep 17 00:00:00 2001
+From: Eric Blake <eblake@redhat.com>
+Date: Wed, 22 Nov 2017 16:25:16 -0600
+Subject: [PATCH] nbd/server: CVE-2017-15119 Reject options larger than 32M
+
+The NBD spec gives us permission to abruptly disconnect on clients
+that send outrageously large option requests, rather than having
+to spend the time reading to the end of the option.  No real
+option request requires that much data anyways; and meanwhile, we
+already have the practice of abruptly dropping the connection on
+any client that sends NBD_CMD_WRITE with a payload larger than 32M.
+
+For comparison, nbdkit drops the connection on any request with
+more than 4096 bytes; however, that limit is probably too low
+(as the NBD spec states an export name can theoretically be up
+to 4096 bytes, which means a valid NBD_OPT_INFO could be even
+longer) - even if qemu doesn't permit exports longer than 256
+bytes.
+
+It could be argued that a malicious client trying to get us to
+read nearly 4G of data on a bad request is a form of denial of
+service.  In particular, if the server requires TLS, but a client
+that does not know the TLS credentials sends any option (other
+than NBD_OPT_STARTTLS or NBD_OPT_EXPORT_NAME) with a stated
+payload of nearly 4G, then the server was keeping the connection
+alive trying to read all the payload, tying up resources that it
+would rather be spending on a client that can get past the TLS
+handshake.  Hence, this warranted a CVE.
+
+Present since at least 2.5 when handling known options, and made
+worse in 2.6 when fixing support for NBD_FLAG_C_FIXED_NEWSTYLE
+to handle unknown options.
+
+CC: qemu-stable@nongnu.org
+Signed-off-by: Eric Blake <eblake@redhat.com>
+---
+ nbd/server.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/nbd/server.c b/nbd/server.c
+index 7d6801b427..a81801e3bc 100644
+--- a/nbd/server.c
++++ b/nbd/server.c
+@@ -673,6 +673,12 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
+         }
+         length = be32_to_cpu(length);
+ 
++        if (length > NBD_MAX_BUFFER_SIZE) {
++            error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
++                       length, NBD_MAX_BUFFER_SIZE);
++            return -EINVAL;
++        }
++
+         trace_nbd_negotiate_options_check_option(option,
+                                                  nbd_opt_lookup(option));
+         if (client->tlscreds &&
+-- 
+2.15.0
+