On Tue, Jan 25, 2022 at 12:58:55AM +0800, Zhou Qingyang wrote:
> In nvkm_acr_hsfw_load_bl(), the return value of kmalloc() is directly
> passed to memcpy(), which could lead to undefined behavior on failure
> of kmalloc().
>
> Fix this bug by using kmemdup() instead of kmalloc()+memcpy().
>
> This bug was found by a static analyzer.
>
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code.
>
> Fixes: 22dcda45a3d1 ("drm/nouveau/acr: implement new subdev to replace "secure boot"")
> Signed-off-by: Zhou Qingyang <zhou1615@xxxxxxx>
> ---
> The analysis employs differential checking to identify inconsistent
> security operations (e.g., checks or kfrees) between two code paths
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs.
>
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
>
> drivers/gpu/drm/nouveau/nvkm/subdev/acr/hsfw.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/acr/hsfw.c b/drivers/gpu/drm/nouveau/nvkm/subdev/acr/hsfw.c
> index 667fa016496e..a6ea89a5d51a 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/acr/hsfw.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/acr/hsfw.c
> @@ -142,11 +142,12 @@ nvkm_acr_hsfw_load_bl(struct nvkm_acr *acr, const char *name, int ver,
>
> hsfw->imem_size = desc->code_size;
> hsfw->imem_tag = desc->start_tag;
> - hsfw->imem = kmalloc(desc->code_size, GFP_KERNEL);
> - memcpy(hsfw->imem, data + desc->code_off, desc->code_size);
> -
> + hsfw->imem = kmemdup(data + desc->code_off, desc->code_size, GFP_KERNEL);
> nvkm_firmware_put(fw);
> - return 0;
> + if (!hsfw->imem)
> + return -ENOMEM;
> + else
> + return 0;
> }
>
> int
> --
> 2.25.1
>
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