Le 01/06/2023 à 19:39, Pierre-Louis Bossart a écrit :
On 6/1/23 12:30, Christophe JAILLET wrote:
struct_size() checks for overflow, but assigning its result to just a u32
may still overflow after a successful check.
Use a size_t instead in order to be cleaner.
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Based on analysis from Dan Carpenter on another patch (see [1]).
[1]: https://lore.kernel.org/all/00e84595-e2c9-48ea-8737-18da34eaafbf@kili.mountain/
looks like there are similar cases of struct_size -> u32 conversions in
other places:
struct snd_sof_control {
u32 size; /* cdata size */
ipc3-topology.c: scontrol->size = struct_size(cdata, chanv,
scontrol->num_channels);
ipc3-topology.c: scontrol->size = struct_size(cdata, chanv,
scontrol->num_channels);
ipc4-topology.c: scontrol->size = struct_size(control_data,
chanv, scontrol->num_channels);
My coccinelle script does not handle such cases.
not sure how much of an issue this really is though?
I agree that in practice it should be safe as-is, but it can't hurt :).
I don't know this code well, but should [2] be part of the call chain,
it is obvious that it CAN'T overflow.
I checked for places where such pattern occurs after Dan's comment on
another patch. I'll see if I find better candidates.
CJ
[2]:
https://elixir.bootlin.com/linux/v6.4-rc1/source/sound/soc/sof/topology.c#L1404
---
sound/soc/sof/ipc4-topology.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/soc/sof/ipc4-topology.c b/sound/soc/sof/ipc4-topology.c
index db64e0cb8663..50faa4c88b97 100644
--- a/sound/soc/sof/ipc4-topology.c
+++ b/sound/soc/sof/ipc4-topology.c
@@ -881,7 +881,7 @@ static int sof_ipc4_widget_setup_comp_process(struct snd_sof_widget *swidget)
/* allocate memory for base config extension if needed */
if (process->init_config == SOF_IPC4_MODULE_INIT_CONFIG_TYPE_BASE_CFG_WITH_EXT) {
struct sof_ipc4_base_module_cfg_ext *base_cfg_ext;
- u32 ext_size = struct_size(base_cfg_ext, pin_formats,
+ size_t ext_size = struct_size(base_cfg_ext, pin_formats,
swidget->num_input_pins + swidget->num_output_pins);
base_cfg_ext = kzalloc(ext_size, GFP_KERNEL);
