[lvc-project] [PATCH v2] media: venus: prevent potential integer overflow in decide_core()

[Pavel Zhigulin]

The function 'decide_core()' contains the following code:

	cur_inst_load = load_per_instance(inst);
	cur_inst_load *= inst->clk_data.vpp_freq;
	...
	cur_inst_lp_load = load_per_instance(inst);
	cur_inst_lp_load *= inst->clk_data.low_power_freq;

This can lead to an integer overflow because the variables
'cur_inst_load' and 'cur_inst_lp_load' are of type u32.

The overflow can occur in the following scenario:

  1. The current FPS is 240 (VENUS_MAX_FPS constant).
     The processed image frame has a resolution of 4096x4096 pixels.
  2. According to 'codec_freq_data':
       - 'inst->clk_data.low_power_freq' can be up to 320
       - 'inst->clk_data.vpp_freq' can be up to 675
     (see drivers/media/platform/qcom/venus/hfi_platform_v4.c
      and drivers/media/platform/qcom/venus/hfi_platform_v6.c)
  3. 'load_per_instance()' returns 15728640 under these conditions.
  4. As a result:
       cur_inst_load *= inst->clk_data.vpp_freq → 10616832000
       cur_inst_lp_load *= inst->clk_data.low_power_freq → 5033164800

The proposed fix changes the type of these variables from u32 to u64
to prevent overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 3cfe5815ce0e ("media: venus: Enable low power setting for encoder")
Signed-off-by: Pavel Zhigulin <Pavel.Zhigulin at kaspersky.com>
---
v2: Revert min_coreid and min_lp_coreid to u32 as
    Dikshita Agarwal <dikshita.agarwal at oss.qualcomm.com> suggested
	during review
v1: https://lore.kernel.org/all/20251006154041.1804800-1-Pavel.Zhigulin@kaspersky.com/
 drivers/media/platform/qcom/venus/pm_helpers.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/qcom/venus/pm_helpers.c b/drivers/media/platform/qcom/venus/pm_helpers.c
index f0269524ac70..eec49590e806 100644
--- a/drivers/media/platform/qcom/venus/pm_helpers.c
+++ b/drivers/media/platform/qcom/venus/pm_helpers.c
@@ -582,9 +582,9 @@ static int move_core_to_power_save_mode(struct venus_core *core,
 }

 static void
-min_loaded_core(struct venus_inst *inst, u32 *min_coreid, u32 *min_load, bool low_power)
+min_loaded_core(struct venus_inst *inst, u32 *min_coreid, u64 *min_load, bool low_power)
 {
-	u32 mbs_per_sec, load, core1_load = 0, core2_load = 0;
+	u64 mbs_per_sec, load, core1_load = 0, core2_load = 0;
 	u32 cores_max = core_num_max(inst);
 	struct venus_core *core = inst->core;
 	struct venus_inst *inst_pos;
@@ -639,8 +639,9 @@ static int decide_core(struct venus_inst *inst)
 {
 	const u32 ptype = HFI_PROPERTY_CONFIG_VIDEOCORES_USAGE;
 	struct venus_core *core = inst->core;
-	u32 min_coreid, min_load, cur_inst_load;
-	u32 min_lp_coreid, min_lp_load, cur_inst_lp_load;
+	u32 min_coreid, min_lp_coreid;
+	u64 min_load, cur_inst_load;
+	u64 min_lp_load, cur_inst_lp_load;
 	struct hfi_videocores_usage_type cu;
 	unsigned long max_freq = ULONG_MAX;
 	struct device *dev = core->dev;
--
2.43.0