[PATCH openEuler-1.0-LTS 0/5] CVE-2023-53998
Herbert Xu (1): hwrng: virtio - Fix race on data_avail and actual data Laurent Vivier (4): hwrng: virtio - add an internal buffer hwrng: virtio - don't wait on cleanup hwrng: virtio - don't waste entropy hwrng: virtio - always add a pending request drivers/char/hw_random/virtio-rng.c | 88 +++++++++++++++++++++-------- 1 file changed, 66 insertions(+), 22 deletions(-) -- 2.34.1
From: Laurent Vivier <lvivier@redhat.com> stable inclusion from stable-v4.19.291 commit e1b23dcbc0d5d433287f8d34d0d8a3b230f6ad92 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12776 CVE: CVE-2023-53998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit bf3175bc50a3754dc427e2f5046e17a9fafc8be7 ] hwrng core uses two buffers that can be mixed in the virtio-rng queue. If the buffer is provided with wait=0 it is enqueued in the virtio-rng queue but unused by the caller. On the next call, core provides another buffer but the first one is filled instead and the new one queued. And the caller reads the data from the new one that is not updated, and the data in the first one are lost. To avoid this mix, virtio-rng needs to use its own unique internal buffer at a cost of a data copy to the caller buffer. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Link: https://lore.kernel.org/r/20211028101111.128049-2-lvivier@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Stable-dep-of: ac52578d6e8d ("hwrng: virtio - Fix race on data_avail and actual data") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/char/hw_random/virtio-rng.c | 43 ++++++++++++++++++++++------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 7abd604e938c..999f523c80c1 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -30,13 +30,20 @@ static DEFINE_IDA(rng_index_ida); struct virtrng_info { struct hwrng hwrng; struct virtqueue *vq; - struct completion have_data; char name[25]; - unsigned int data_avail; int index; bool busy; bool hwrng_register_done; bool hwrng_removed; + /* data transfer */ + struct completion have_data; + unsigned int data_avail; + /* minimal size returned by rng_buffer_size() */ +#if SMP_CACHE_BYTES < 32 + u8 data[32]; +#else + u8 data[SMP_CACHE_BYTES]; +#endif }; static void random_recv_done(struct virtqueue *vq) @@ -51,14 +58,14 @@ static void random_recv_done(struct virtqueue *vq) } /* The host will fill any buffer we give it with sweet, sweet randomness. */ -static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) +static void register_buffer(struct virtrng_info *vi) { struct scatterlist sg; - sg_init_one(&sg, buf, size); + sg_init_one(&sg, vi->data, sizeof(vi->data)); /* There should always be room for one buffer. */ - virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); + virtqueue_add_inbuf(vi->vq, &sg, 1, vi->data, GFP_KERNEL); virtqueue_kick(vi->vq); } @@ -67,6 +74,8 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) { int ret; struct virtrng_info *vi = (struct virtrng_info *)rng->priv; + unsigned int chunk; + size_t read; if (vi->hwrng_removed) return -ENODEV; @@ -74,19 +83,33 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) if (!vi->busy) { vi->busy = true; reinit_completion(&vi->have_data); - register_buffer(vi, buf, size); + register_buffer(vi); } if (!wait) return 0; - ret = wait_for_completion_killable(&vi->have_data); - if (ret < 0) - return ret; + read = 0; + while (size != 0) { + ret = wait_for_completion_killable(&vi->have_data); + if (ret < 0) + return ret; + + chunk = min_t(unsigned int, size, vi->data_avail); + memcpy(buf + read, vi->data, chunk); + read += chunk; + size -= chunk; + vi->data_avail = 0; + + if (size != 0) { + reinit_completion(&vi->have_data); + register_buffer(vi); + } + } vi->busy = false; - return vi->data_avail; + return read; } static void virtio_cleanup(struct hwrng *rng) -- 2.34.1
From: Laurent Vivier <lvivier@redhat.com> stable inclusion from stable-v4.19.291 commit eaf91a80bd476e2f2978977b8560a9b2d0cb2701 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12776 CVE: CVE-2023-53998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 2bb31abdbe55742c89f4dc0cc26fcbc8467364f6 ] When virtio-rng device was dropped by the hwrng core we were forced to wait the buffer to come back from the device to not have remaining ongoing operation that could spoil the buffer. But now, as the buffer is internal to the virtio-rng we can release the waiting loop immediately, the buffer will be retrieve and use when the virtio-rng driver will be selected again. This avoids to hang on an rng_current write command if the virtio-rng device is blocked by a lack of entropy. This allows to select another entropy source if the current one is empty. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Link: https://lore.kernel.org/r/20211028101111.128049-3-lvivier@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Stable-dep-of: ac52578d6e8d ("hwrng: virtio - Fix race on data_avail and actual data") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/char/hw_random/virtio-rng.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 999f523c80c1..9a3fbd2b4110 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -94,6 +94,11 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) ret = wait_for_completion_killable(&vi->have_data); if (ret < 0) return ret; + /* if vi->data_avail is 0, we have been interrupted + * by a cleanup, but buffer stays in the queue + */ + if (vi->data_avail == 0) + return read; chunk = min_t(unsigned int, size, vi->data_avail); memcpy(buf + read, vi->data, chunk); @@ -117,7 +122,7 @@ static void virtio_cleanup(struct hwrng *rng) struct virtrng_info *vi = (struct virtrng_info *)rng->priv; if (vi->busy) - wait_for_completion(&vi->have_data); + complete(&vi->have_data); } static int probe_common(struct virtio_device *vdev) -- 2.34.1
From: Laurent Vivier <lvivier@redhat.com> stable inclusion from stable-v4.19.291 commit b2add01643b9c7a7fb9c02ae272bd4dbedaa1520 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12776 CVE: CVE-2023-53998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 5c8e933050044d6dd2a000f9a5756ae73cbe7c44 ] if we don't use all the entropy available in the buffer, keep it and use it later. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Link: https://lore.kernel.org/r/20211028101111.128049-4-lvivier@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Stable-dep-of: ac52578d6e8d ("hwrng: virtio - Fix race on data_avail and actual data") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/char/hw_random/virtio-rng.c | 52 +++++++++++++++++++---------- 1 file changed, 35 insertions(+), 17 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 9a3fbd2b4110..c88f175e60a4 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -38,6 +38,7 @@ struct virtrng_info { /* data transfer */ struct completion have_data; unsigned int data_avail; + unsigned int data_idx; /* minimal size returned by rng_buffer_size() */ #if SMP_CACHE_BYTES < 32 u8 data[32]; @@ -54,6 +55,9 @@ static void random_recv_done(struct virtqueue *vq) if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) return; + vi->data_idx = 0; + vi->busy = false; + complete(&vi->have_data); } @@ -70,6 +74,16 @@ static void register_buffer(struct virtrng_info *vi) virtqueue_kick(vi->vq); } +static unsigned int copy_data(struct virtrng_info *vi, void *buf, + unsigned int size) +{ + size = min_t(unsigned int, size, vi->data_avail); + memcpy(buf, vi->data + vi->data_idx, size); + vi->data_idx += size; + vi->data_avail -= size; + return size; +} + static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) { int ret; @@ -80,17 +94,29 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) if (vi->hwrng_removed) return -ENODEV; - if (!vi->busy) { - vi->busy = true; - reinit_completion(&vi->have_data); - register_buffer(vi); + read = 0; + + /* copy available data */ + if (vi->data_avail) { + chunk = copy_data(vi, buf, size); + size -= chunk; + read += chunk; } if (!wait) - return 0; + return read; - read = 0; + /* We have already copied available entropy, + * so either size is 0 or data_avail is 0 + */ while (size != 0) { + /* data_avail is 0 */ + if (!vi->busy) { + /* no pending request, ask for more */ + vi->busy = true; + reinit_completion(&vi->have_data); + register_buffer(vi); + } ret = wait_for_completion_killable(&vi->have_data); if (ret < 0) return ret; @@ -100,20 +126,11 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) if (vi->data_avail == 0) return read; - chunk = min_t(unsigned int, size, vi->data_avail); - memcpy(buf + read, vi->data, chunk); - read += chunk; + chunk = copy_data(vi, buf + read, size); size -= chunk; - vi->data_avail = 0; - - if (size != 0) { - reinit_completion(&vi->have_data); - register_buffer(vi); - } + read += chunk; } - vi->busy = false; - return read; } @@ -173,6 +190,7 @@ static void remove_common(struct virtio_device *vdev) vi->hwrng_removed = true; vi->data_avail = 0; + vi->data_idx = 0; complete(&vi->have_data); vdev->config->reset(vdev); vi->busy = false; -- 2.34.1
From: Laurent Vivier <lvivier@redhat.com> stable inclusion from stable-v4.19.291 commit bdc0580d6e694e1ad42a26d7d24c208c2eac7204 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12776 CVE: CVE-2023-53998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 9a4b612d675b03f7fc9fa1957ca399c8223f3954 ] If we ensure we have already some data available by enqueuing again the buffer once data are exhausted, we can return what we have without waiting for the device answer. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Link: https://lore.kernel.org/r/20211028101111.128049-5-lvivier@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Stable-dep-of: ac52578d6e8d ("hwrng: virtio - Fix race on data_avail and actual data") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/char/hw_random/virtio-rng.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index c88f175e60a4..a84248c26fd7 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -32,7 +32,6 @@ struct virtrng_info { struct virtqueue *vq; char name[25]; int index; - bool busy; bool hwrng_register_done; bool hwrng_removed; /* data transfer */ @@ -56,16 +55,18 @@ static void random_recv_done(struct virtqueue *vq) return; vi->data_idx = 0; - vi->busy = false; complete(&vi->have_data); } -/* The host will fill any buffer we give it with sweet, sweet randomness. */ -static void register_buffer(struct virtrng_info *vi) +static void request_entropy(struct virtrng_info *vi) { struct scatterlist sg; + reinit_completion(&vi->have_data); + vi->data_avail = 0; + vi->data_idx = 0; + sg_init_one(&sg, vi->data, sizeof(vi->data)); /* There should always be room for one buffer. */ @@ -81,6 +82,8 @@ static unsigned int copy_data(struct virtrng_info *vi, void *buf, memcpy(buf, vi->data + vi->data_idx, size); vi->data_idx += size; vi->data_avail -= size; + if (vi->data_avail == 0) + request_entropy(vi); return size; } @@ -110,13 +113,7 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) * so either size is 0 or data_avail is 0 */ while (size != 0) { - /* data_avail is 0 */ - if (!vi->busy) { - /* no pending request, ask for more */ - vi->busy = true; - reinit_completion(&vi->have_data); - register_buffer(vi); - } + /* data_avail is 0 but a request is pending */ ret = wait_for_completion_killable(&vi->have_data); if (ret < 0) return ret; @@ -138,8 +135,7 @@ static void virtio_cleanup(struct hwrng *rng) { struct virtrng_info *vi = (struct virtrng_info *)rng->priv; - if (vi->busy) - complete(&vi->have_data); + complete(&vi->have_data); } static int probe_common(struct virtio_device *vdev) @@ -175,6 +171,9 @@ static int probe_common(struct virtio_device *vdev) goto err_find; } + /* we always have a pending entropy request */ + request_entropy(vi); + return 0; err_find: @@ -193,7 +192,6 @@ static void remove_common(struct virtio_device *vdev) vi->data_idx = 0; complete(&vi->have_data); vdev->config->reset(vdev); - vi->busy = false; if (vi->hwrng_register_done) hwrng_unregister(&vi->hwrng); vdev->config->del_vqs(vdev); -- 2.34.1
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From: Herbert Xu <herbert@gondor.apana.org.au> stable inclusion from stable-v4.19.291 commit 241ef15776a7c8505008db689175b320d345ecd3 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12776 CVE: CVE-2023-53998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit ac52578d6e8d300dd50f790f29a24169b1edd26c ] The virtio rng device kicks off a new entropy request whenever the data available reaches zero. When a new request occurs at the end of a read operation, that is, when the result of that request is only needed by the next reader, then there is a race between the writing of the new data and the next reader. This is because there is no synchronisation whatsoever between the writer and the reader. Fix this by writing data_avail with smp_store_release and reading it with smp_load_acquire when we first enter read. The subsequent reads are safe because they're either protected by the first load acquire, or by the completion mechanism. Also remove the redundant zeroing of data_idx in random_recv_done (data_idx must already be zero at this point) and data_avail in request_entropy (ditto). Reported-by: syzbot+726dc8c62c3536431ceb@syzkaller.appspotmail.com Fixes: f7f510ec1957 ("virtio: An entropy device, as suggested by hpa.") Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/char/hw_random/virtio-rng.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index a84248c26fd7..58884d875201 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -17,6 +17,7 @@ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ +#include <asm/barrier.h> #include <linux/err.h> #include <linux/hw_random.h> #include <linux/scatterlist.h> @@ -49,13 +50,13 @@ struct virtrng_info { static void random_recv_done(struct virtqueue *vq) { struct virtrng_info *vi = vq->vdev->priv; + unsigned int len; /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ - if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) + if (!virtqueue_get_buf(vi->vq, &len)) return; - vi->data_idx = 0; - + smp_store_release(&vi->data_avail, len); complete(&vi->have_data); } @@ -64,7 +65,6 @@ static void request_entropy(struct virtrng_info *vi) struct scatterlist sg; reinit_completion(&vi->have_data); - vi->data_avail = 0; vi->data_idx = 0; sg_init_one(&sg, vi->data, sizeof(vi->data)); @@ -100,7 +100,7 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) read = 0; /* copy available data */ - if (vi->data_avail) { + if (smp_load_acquire(&vi->data_avail)) { chunk = copy_data(vi, buf, size); size -= chunk; read += chunk; -- 2.34.1
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