qemu: Security fix CVE-2016-2858

Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 183 insertions, 0 deletions

diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2016-2858.patch b/meta/recipes-devtools/qemu/qemu/CVE-2016-2858.patch
new file mode 100644
index 0000000000..d5395e6152
--- /dev/null
+++ b/meta/recipes-devtools/qemu/qemu/CVE-2016-2858.patch
@@ -0,0 +1,183 @@
+From 60253ed1e6ec6d8e5ef2efe7bf755f475dce9956 Mon Sep 17 00:00:00 2001
+From: Ladi Prosek <lprosek@redhat.com>
+Date: Thu, 3 Mar 2016 09:37:18 +0100
+Subject: [PATCH] rng: add request queue support to rng-random
+
+Requests are now created in the RngBackend parent class and the
+code path is shared by both rng-egd and rng-random.
+
+This commit fixes the rng-random implementation which processed
+only one request at a time and simply discarded all but the most
+recent one. In the guest this manifested as delayed completion
+of reads from virtio-rng, i.e. a read was completed only after
+another read was issued.
+
+By switching rng-random to use the same request queue as rng-egd,
+the unsafe stack-based allocation of the entropy buffer is
+eliminated and replaced with g_malloc.
+
+Signed-off-by: Ladi Prosek <lprosek@redhat.com>
+Reviewed-by: Amit Shah <amit.shah@redhat.com>
+Message-Id: <1456994238-9585-5-git-send-email-lprosek@redhat.com>
+Signed-off-by: Amit Shah <amit.shah@redhat.com>
+
+Upstream-Status: Backport
+CVE: CVE-2016-2858
+
+http://git.qemu.org/?p=qemu.git;a=commit;h=60253ed1e6ec6d8e5ef2efe7bf755f475
+Signed-off-by: Armin Kuster <akuster@mvista.com>
+
+---
+ backends/rng-egd.c    | 16 ++--------------
+ backends/rng-random.c | 43 +++++++++++++++++++------------------------
+ backends/rng.c        | 13 ++++++++++++-
+ include/sysemu/rng.h  |  3 +--
+ 4 files changed, 34 insertions(+), 41 deletions(-)
+
+Index: qemu-2.5.0/backends/rng-egd.c
+===================================================================
+--- qemu-2.5.0.orig/backends/rng-egd.c
++++ qemu-2.5.0/backends/rng-egd.c
+@@ -26,20 +26,10 @@ typedef struct RngEgd
+     char *chr_name;
+ } RngEgd;
+ 
+-static void rng_egd_request_entropy(RngBackend *b, size_t size,
+-                                    EntropyReceiveFunc *receive_entropy,
+-                                    void *opaque)
++static void rng_egd_request_entropy(RngBackend *b, RngRequest *req)
+ {
+     RngEgd *s = RNG_EGD(b);
+-    RngRequest *req;
+-
+-    req = g_malloc(sizeof(*req));
+-
+-    req->offset = 0;
+-    req->size = size;
+-    req->receive_entropy = receive_entropy;
+-    req->opaque = opaque;
+-    req->data = g_malloc(req->size);
++    size_t size = req->size;
+ 
+     while (size > 0) {
+         uint8_t header[2];
+@@ -53,8 +43,6 @@ static void rng_egd_request_entropy(RngB
+ 
+         size -= len;
+     }
+-
+-    s->parent.requests = g_slist_append(s->parent.requests, req);
+ }
+ 
+ static int rng_egd_chr_can_read(void *opaque)
+Index: qemu-2.5.0/backends/rng-random.c
+===================================================================
+--- qemu-2.5.0.orig/backends/rng-random.c
++++ qemu-2.5.0/backends/rng-random.c
+@@ -21,10 +21,6 @@ struct RndRandom
+ 
+     int fd;
+     char *filename;
+-
+-    EntropyReceiveFunc *receive_func;
+-    void *opaque;
+-    size_t size;
+ };
+ 
+ /**
+@@ -37,36 +33,35 @@ struct RndRandom
+ static void entropy_available(void *opaque)
+ {
+     RndRandom *s = RNG_RANDOM(opaque);
+-    uint8_t buffer[s->size];
+-    ssize_t len;
+ 
+-    len = read(s->fd, buffer, s->size);
+-    if (len < 0 && errno == EAGAIN) {
+-        return;
+-    }
+-    g_assert(len != -1);
++    while (s->parent.requests != NULL) {
++        RngRequest *req = s->parent.requests->data;
++        ssize_t len;
++
++        len = read(s->fd, req->data, req->size);
++        if (len < 0 && errno == EAGAIN) {
++            return;
++        }
++        g_assert(len != -1);
++
++        req->receive_entropy(req->opaque, req->data, len);
+ 
+-    s->receive_func(s->opaque, buffer, len);
+-    s->receive_func = NULL;
++        rng_backend_finalize_request(&s->parent, req);
++    }
+ 
++    /* We've drained all requests, the fd handler can be reset. */
+     qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+ }
+ 
+-static void rng_random_request_entropy(RngBackend *b, size_t size,
+-                                        EntropyReceiveFunc *receive_entropy,
+-                                        void *opaque)
++static void rng_random_request_entropy(RngBackend *b, RngRequest *req)
+ {
+     RndRandom *s = RNG_RANDOM(b);
+ 
+-    if (s->receive_func) {
+-        s->receive_func(s->opaque, NULL, 0);
++    if (s->parent.requests == NULL) {
++        /* If there are no pending requests yet, we need to
++         * install our fd handler. */
++        qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
+     }
+-
+-    s->receive_func = receive_entropy;
+-    s->opaque = opaque;
+-    s->size = size;
+-
+-    qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
+ }
+ 
+ static void rng_random_opened(RngBackend *b, Error **errp)
+Index: qemu-2.5.0/backends/rng.c
+===================================================================
+--- qemu-2.5.0.orig/backends/rng.c
++++ qemu-2.5.0/backends/rng.c
+@@ -19,9 +19,20 @@ void rng_backend_request_entropy(RngBack
+                                  void *opaque)
+ {
+     RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
++    RngRequest *req;
+ 
+     if (k->request_entropy) {
+-        k->request_entropy(s, size, receive_entropy, opaque);
++        req = g_malloc(sizeof(*req));
++
++        req->offset = 0;
++        req->size = size;
++        req->receive_entropy = receive_entropy;
++        req->opaque = opaque;
++        req->data = g_malloc(req->size);
++
++        k->request_entropy(s, req);
++
++        s->requests = g_slist_append(s->requests, req);
+     }
+ }
+ 
+Index: qemu-2.5.0/include/sysemu/rng.h
+===================================================================
+--- qemu-2.5.0.orig/include/sysemu/rng.h
++++ qemu-2.5.0/include/sysemu/rng.h
+@@ -46,8 +46,7 @@ struct RngBackendClass
+ {
+     ObjectClass parent_class;
+ 
+-    void (*request_entropy)(RngBackend *s, size_t size,
+-                            EntropyReceiveFunc *receive_entropy, void *opaque);
++    void (*request_entropy)(RngBackend *s, RngRequest *req);
+ 
+     void (*opened)(RngBackend *s, Error **errp);
+ };