From a9580b9b36a88f8cc92ae52820a386f92c8d6065 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Fri, 20 Oct 2023 19:56:59 +0000 Subject: [PATCH 1/3] rpmsg: core: Replace deprecated strncpy with strscpy strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect chinfo.name to be NUL-terminated based on its usage with strncmp(): rpmsg_core.c: 389: if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE)) Moreover, NUL-padding is not required as chinfo has stack default initialized all fields to zero: rpmsg_core.c: 539: struct rpmsg_channel_info chinfo = {}; Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. Also, favor the more idiomatic strscpy() usage of: (dest, src, sizeof(dest)). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Link: https://lore.kernel.org/r/20231020-strncpy-drivers-rpmsg-rpmsg_core-c-v1-1-a86b7930c1cf@google.com Signed-off-by: Mathieu Poirier --- drivers/rpmsg/rpmsg_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c index 32b550c91d9f..8abc7d022ff7 100644 --- a/drivers/rpmsg/rpmsg_core.c +++ b/drivers/rpmsg/rpmsg_core.c @@ -545,7 +545,7 @@ static int rpmsg_dev_probe(struct device *dev) goto out; if (rpdrv->callback) { - strncpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE); + strscpy(chinfo.name, rpdev->id.name, sizeof(chinfo.name)); chinfo.src = rpdev->src; chinfo.dst = RPMSG_ADDR_ANY; From ec189da923fb06acb0ee38e2d0ee55239995e9d6 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Fri, 20 Oct 2023 23:18:59 +0000 Subject: [PATCH 2/3] rpmsg: Replace deprecated strncpy with strscpy_pad strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect chinfo.name to be NUL-terminated based on its use with format strings: | dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name); Since chinfo is not default initialized, we should NUL-pad the `name` field so that the behavior is consistent with what strncpy() provides: | struct rpmsg_channel_info chinfo; Considering the above, a suitable replacement is `strscpy_pad` due to the fact that it guarantees both NUL-termination and NUL-padding on the destination buffer. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Link: https://lore.kernel.org/r/20231020-strncpy-drivers-rpmsg-rpmsg_ns-c-v1-1-99b16b00c36c@google.com Signed-off-by: Mathieu Poirier --- drivers/rpmsg/rpmsg_ns.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c index c70ad03ff2e9..bde8c8d433e0 100644 --- a/drivers/rpmsg/rpmsg_ns.c +++ b/drivers/rpmsg/rpmsg_ns.c @@ -50,7 +50,7 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len, /* don't trust the remote processor for null terminating the name */ msg->name[RPMSG_NAME_SIZE - 1] = '\0'; - strncpy(chinfo.name, msg->name, sizeof(chinfo.name)); + strscpy_pad(chinfo.name, msg->name, sizeof(chinfo.name)); chinfo.src = RPMSG_ADDR_ANY; chinfo.dst = rpmsg32_to_cpu(rpdev, msg->addr); From 2a6e483ad047654a220c798080d0fc861ead2e07 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Mon, 23 Oct 2023 18:12:28 +0000 Subject: [PATCH 3/3] rpmsg: virtio: Replace deprecated strncpy with strscpy/_pad strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. This patch replaces 3 callsites of strncpy(). The first two populate the destination buffer `nsm.name` -- which we expect to be NUL-terminated based on their use with format strings. Firstly, as I understand it, virtio_rpmsg_announce_create() creates an rpmsg_ns_msg and sends via: virtio_rpmsg_bus.c: 336: err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR); ... which uses: virtio_rpmsg_sendto() -> rpmsg_send_offchannel_raw() ... which copies its data into an rpmsg_hdr `msg` in virtio_rpmsg_bus.c 618: memcpy(msg->data, data, len); This callback is invoked when a message is received from the remote processor: rpmsg_ns.c: 30: /* invoked when a name service announcement arrives */ 31: static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len, 32: void *priv, u32 src) 33: { 34: struct rpmsg_ns_msg *msg = data; ... 50: /* don't trust the remote processor for null terminating the name */ 51: msg->name[RPMSG_NAME_SIZE - 1] = '\0'; ... which leads into the use of `name` within a format string: rpmsg_ns.c: 57: dev_info(dev, "%sing channel %s addr 0x%x\n", 58: rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_NS_DESTROY ? 59: "destroy" : "creat", msg->name, chinfo.dst); We can also observe that `nsm` is not zero-initialized and as such we should maintain the NUL-padding behavior that strncpy() provides: virtio_rpmsg_bus.c: 330: struct rpmsg_ns_msg nsm; Considering the above, a suitable replacement is `strscpy_pad` due to the fact that it guarantees both NUL-termination and NUL-padding on the destination buffer. Now, for the third and final destination buffer rpdev->id.name we can just go for strscpy() (not _pad()) as rpdev points to &vch->rpdev: | rpdev = &vch->rpdev; ... and vch is zero-allocated: | vch = kzalloc(sizeof(*vch), GFP_KERNEL); ... this renders any additional NUL-byte assignments (like the ones strncpy() or strscpy_pad() does) redundant. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Link: https://lore.kernel.org/r/20231023-strncpy-drivers-rpmsg-virtio_rpmsg_bus-c-v2-1-dc591c36f5ed@google.com Signed-off-by: Mathieu Poirier --- drivers/rpmsg/virtio_rpmsg_bus.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 905ac7910c98..dc87965f8164 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -329,7 +329,7 @@ static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev) virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) { struct rpmsg_ns_msg nsm; - strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE); + strscpy_pad(nsm.name, rpdev->id.name, sizeof(nsm.name)); nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr); nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_CREATE); @@ -353,7 +353,7 @@ static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev) virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) { struct rpmsg_ns_msg nsm; - strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE); + strscpy_pad(nsm.name, rpdev->id.name, sizeof(nsm.name)); nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr); nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_DESTROY); @@ -424,7 +424,7 @@ static struct rpmsg_device *__rpmsg_create_channel(struct virtproc_info *vrp, */ rpdev->announce = rpdev->src != RPMSG_ADDR_ANY; - strncpy(rpdev->id.name, chinfo->name, RPMSG_NAME_SIZE); + strscpy(rpdev->id.name, chinfo->name, sizeof(rpdev->id.name)); rpdev->dev.parent = &vrp->vdev->dev; rpdev->dev.release = virtio_rpmsg_release_device;