[PATCH] samples: Replace strlcpy() with strscpy()

From: Kees Cook
Date: Thu Nov 16 2023 - 14:15:17 EST


strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
Link: https://github.com/KSPP/linux/issues/89 [2]
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: Geliang Tang <geliang.tang@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
samples/trace_events/trace-events-sample.h | 2 +-
samples/v4l/v4l2-pci-skeleton.c | 10 +++++-----
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
index 1c6b843b8c4e..23f923ccd529 100644
--- a/samples/trace_events/trace-events-sample.h
+++ b/samples/trace_events/trace-events-sample.h
@@ -305,7 +305,7 @@ TRACE_EVENT(foo_bar,
),

TP_fast_assign(
- strlcpy(__entry->foo, foo, 10);
+ strscpy(__entry->foo, foo, 10);
__entry->bar = bar;
memcpy(__get_dynamic_array(list), lst,
__length_of(lst) * sizeof(int));
diff --git a/samples/v4l/v4l2-pci-skeleton.c b/samples/v4l/v4l2-pci-skeleton.c
index a61f94db18d9..69ef788d9e3b 100644
--- a/samples/v4l/v4l2-pci-skeleton.c
+++ b/samples/v4l/v4l2-pci-skeleton.c
@@ -291,8 +291,8 @@ static int skeleton_querycap(struct file *file, void *priv,
{
struct skeleton *skel = video_drvdata(file);

- strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
- strlcpy(cap->card, "V4L2 PCI Skeleton", sizeof(cap->card));
+ strscpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
+ strscpy(cap->card, "V4L2 PCI Skeleton", sizeof(cap->card));
snprintf(cap->bus_info, sizeof(cap->bus_info), "PCI:%s",
pci_name(skel->pdev));
return 0;
@@ -597,11 +597,11 @@ static int skeleton_enum_input(struct file *file, void *priv,
i->type = V4L2_INPUT_TYPE_CAMERA;
if (i->index == 0) {
i->std = SKEL_TVNORMS;
- strlcpy(i->name, "S-Video", sizeof(i->name));
+ strscpy(i->name, "S-Video", sizeof(i->name));
i->capabilities = V4L2_IN_CAP_STD;
} else {
i->std = 0;
- strlcpy(i->name, "HDMI", sizeof(i->name));
+ strscpy(i->name, "HDMI", sizeof(i->name));
i->capabilities = V4L2_IN_CAP_DV_TIMINGS;
}
return 0;
@@ -845,7 +845,7 @@ static int skeleton_probe(struct pci_dev *pdev, const struct pci_device_id *ent)

/* Initialize the video_device structure */
vdev = &skel->vdev;
- strlcpy(vdev->name, KBUILD_MODNAME, sizeof(vdev->name));
+ strscpy(vdev->name, KBUILD_MODNAME, sizeof(vdev->name));
/*
* There is nothing to clean up, so release is set to an empty release
* function. The release callback must be non-NULL.
--
2.34.1