On Mon, Jan 22, 2024 at 04:27:45PM -0800, Kees Cook wrote: > In an effort to separate intentional arithmetic wrap-around from > unexpected wrap-around, we need to refactor places that depend on this > kind of math. One of the most common code patterns of this is: > > VAR + value < VAR > > Notably, this is considered "undefined behavior" for signed and pointer > types, which the kernel works around by using the -fno-strict-overflow > option in the build[1] (which used to just be -fwrapv). Regardless, we > want to get the kernel source to the position where we can meaningfully > instrument arithmetic wrap-around conditions and catch them when they > are unexpected, regardless of whether they are signed[2], unsigned[3], > or pointer[4] types. > > Refactor open-coded wrap-around addition test to use add_would_overflow(). > This paves the way to enabling the wrap-around sanitizers in the future. > > Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] > Link: https://github.com/KSPP/linux/issues/26 [2] > Link: https://github.com/KSPP/linux/issues/27 [3] > Link: https://github.com/KSPP/linux/issues/344 [4] > Cc: Bjorn Andersson <andersson@xxxxxxxxxx> Acked-by: Bjorn Andersson <andersson@xxxxxxxxxx> Regards, Bjorn > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> > Cc: linux-remoteproc@xxxxxxxxxxxxxxx > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > drivers/remoteproc/pru_rproc.c | 2 +- > drivers/remoteproc/remoteproc_elf_loader.c | 2 +- > drivers/remoteproc/remoteproc_virtio.c | 4 ++-- > 3 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c > index 327f0c7ee3d6..834249ee3dd3 100644 > --- a/drivers/remoteproc/pru_rproc.c > +++ b/drivers/remoteproc/pru_rproc.c > @@ -893,7 +893,7 @@ pru_rproc_find_interrupt_map(struct device *dev, const struct firmware *fw) > continue; > > /* make sure we have the entire irq map */ > - if (offset + size > fw->size || offset + size < size) { > + if (offset + size > fw->size || add_would_overflow(size, offset)) { > dev_err(dev, ".pru_irq_map section truncated\n"); > return ERR_PTR(-EINVAL); > } > diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c > index 94177e416047..b9231cf46d68 100644 > --- a/drivers/remoteproc/remoteproc_elf_loader.c > +++ b/drivers/remoteproc/remoteproc_elf_loader.c > @@ -278,7 +278,7 @@ find_table(struct device *dev, const struct firmware *fw) > table = (struct resource_table *)(elf_data + offset); > > /* make sure we have the entire table */ > - if (offset + size > fw_size || offset + size < size) { > + if (offset + size > fw_size || add_would_overflow(size, offset)) { > dev_err(dev, "resource table truncated\n"); > return NULL; > } > diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c > index 83d76915a6ad..58742c666e35 100644 > --- a/drivers/remoteproc/remoteproc_virtio.c > +++ b/drivers/remoteproc/remoteproc_virtio.c > @@ -298,7 +298,7 @@ static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset, > rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset; > cfg = &rsc->vring[rsc->num_of_vrings]; > > - if (offset + len > rsc->config_len || offset + len < len) { > + if (offset + len > rsc->config_len || add_would_overflow(len, offset)) { > dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n"); > return; > } > @@ -316,7 +316,7 @@ static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset, > rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset; > cfg = &rsc->vring[rsc->num_of_vrings]; > > - if (offset + len > rsc->config_len || offset + len < len) { > + if (offset + len > rsc->config_len || add_would_overflow(len, offset)) { > dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n"); > return; > } > -- > 2.34.1 >
