[asahilinux:bits/090-spi-hid 18/22] drivers/soc/apple/rtkit-helper.c:46 apple_rtkit_helper_shmem_setup() warn: variable dereferenced before check 'helper->sram' (see line 35)

From: Dan Carpenter
Date: Mon Sep 19 2022 - 04:48:21 EST


tree: https://github.com/AsahiLinux/linux bits/090-spi-hid
head: ecf1fb81499a2f1724cb90497ca3c1cec831c9b6
commit: 51f1f2b38adcb95f2e04665ae54fe99ba6bd7844 [18/22] soc: apple: Add RTKit helper driver
config: arm-randconfig-m041-20220918
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
drivers/soc/apple/rtkit-helper.c:46 apple_rtkit_helper_shmem_setup() warn: variable dereferenced before check 'helper->sram' (see line 35)

vim +46 drivers/soc/apple/rtkit-helper.c

51f1f2b38adcb9 Hector Martin 2022-07-03 28 static int apple_rtkit_helper_shmem_setup(void *cookie, struct apple_rtkit_shmem *bfr)
51f1f2b38adcb9 Hector Martin 2022-07-03 29 {
51f1f2b38adcb9 Hector Martin 2022-07-03 30 struct apple_rtkit_helper *helper = cookie;
51f1f2b38adcb9 Hector Martin 2022-07-03 31 struct resource res = {
51f1f2b38adcb9 Hector Martin 2022-07-03 32 .start = bfr->iova,
51f1f2b38adcb9 Hector Martin 2022-07-03 33 .end = bfr->iova + bfr->size - 1,
51f1f2b38adcb9 Hector Martin 2022-07-03 34 .name = "rtkit_map",
51f1f2b38adcb9 Hector Martin 2022-07-03 @35 .flags = helper->sram->flags,
^^^^^^^^^^^^^
Dereference

51f1f2b38adcb9 Hector Martin 2022-07-03 36 };
51f1f2b38adcb9 Hector Martin 2022-07-03 37
51f1f2b38adcb9 Hector Martin 2022-07-03 38 if (!bfr->iova) {
51f1f2b38adcb9 Hector Martin 2022-07-03 39 bfr->buffer = dma_alloc_coherent(helper->dev, bfr->size,
51f1f2b38adcb9 Hector Martin 2022-07-03 40 &bfr->iova, GFP_KERNEL);
51f1f2b38adcb9 Hector Martin 2022-07-03 41 if (!bfr->buffer)
51f1f2b38adcb9 Hector Martin 2022-07-03 42 return -ENOMEM;
51f1f2b38adcb9 Hector Martin 2022-07-03 43 return 0;
51f1f2b38adcb9 Hector Martin 2022-07-03 44 }
51f1f2b38adcb9 Hector Martin 2022-07-03 45
51f1f2b38adcb9 Hector Martin 2022-07-03 @46 if (!helper->sram) {
^^^^^^^^^^^^
Checked too late.

51f1f2b38adcb9 Hector Martin 2022-07-03 47 dev_err(helper->dev,
51f1f2b38adcb9 Hector Martin 2022-07-03 48 "RTKit buffer request with no SRAM region: %pR", &res);
51f1f2b38adcb9 Hector Martin 2022-07-03 49 return -EFAULT;
51f1f2b38adcb9 Hector Martin 2022-07-03 50 }
51f1f2b38adcb9 Hector Martin 2022-07-03 51
51f1f2b38adcb9 Hector Martin 2022-07-03 52 if (res.end < res.start || !resource_contains(helper->sram, &res)) {
51f1f2b38adcb9 Hector Martin 2022-07-03 53 dev_err(helper->dev,
51f1f2b38adcb9 Hector Martin 2022-07-03 54 "RTKit buffer request outside SRAM region: %pR", &res);
51f1f2b38adcb9 Hector Martin 2022-07-03 55 return -EFAULT;
51f1f2b38adcb9 Hector Martin 2022-07-03 56 }
51f1f2b38adcb9 Hector Martin 2022-07-03 57
51f1f2b38adcb9 Hector Martin 2022-07-03 58 bfr->iomem = helper->sram_base + (res.start - helper->sram->start);
51f1f2b38adcb9 Hector Martin 2022-07-03 59 bfr->is_mapped = true;
51f1f2b38adcb9 Hector Martin 2022-07-03 60
51f1f2b38adcb9 Hector Martin 2022-07-03 61 return 0;
51f1f2b38adcb9 Hector Martin 2022-07-03 62 }