drm/amdgpu/pm: Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this
uses the maximum sane buffer size and removes copy/paste code.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Reviewed-by: Rex Zhu <rezhu@amd.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index f1404adc3a9016c681d968ed4a3e340ee3c0d139..15a1192c1ec5472b9d4b51127cc7ad569eced99a 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -606,40 +606,59 @@ static ssize_t amdgpu_get_pp_dpm_sclk(struct device *dev,
                return snprintf(buf, PAGE_SIZE, "\n");
 }
 
-static ssize_t amdgpu_set_pp_dpm_sclk(struct device *dev,
-               struct device_attribute *attr,
-               const char *buf,
-               size_t count)
+/*
+ * Worst case: 32 bits individually specified, in octal at 12 characters
+ * per line (+1 for \n).
+ */
+#define AMDGPU_MASK_BUF_MAX    (32 * 13)
+
+static ssize_t amdgpu_read_mask(const char *buf, size_t count, uint32_t *mask)
 {
-       struct drm_device *ddev = dev_get_drvdata(dev);
-       struct amdgpu_device *adev = ddev->dev_private;
        int ret;
        long level;
-       uint32_t mask = 0;
        char *sub_str = NULL;
        char *tmp;
-       char buf_cpy[count];
+       char buf_cpy[AMDGPU_MASK_BUF_MAX + 1];
        const char delimiter[3] = {' ', '\n', '\0'};
+       size_t bytes;
 
-       memcpy(buf_cpy, buf, count+1);
+       *mask = 0;
+
+       bytes = min(count, sizeof(buf_cpy) - 1);
+       memcpy(buf_cpy, buf, bytes);
+       buf_cpy[bytes] = '\0';
        tmp = buf_cpy;
        while (tmp[0]) {
-               sub_str =  strsep(&tmp, delimiter);
+               sub_str = strsep(&tmp, delimiter);
                if (strlen(sub_str)) {
                        ret = kstrtol(sub_str, 0, &level);
-
-                       if (ret) {
-                               count = -EINVAL;
-                               goto fail;
-                       }
-                       mask |= 1 << level;
+                       if (ret)
+                               return -EINVAL;
+                       *mask |= 1 << level;
                } else
                        break;
        }
+
+       return 0;
+}
+
+static ssize_t amdgpu_set_pp_dpm_sclk(struct device *dev,
+               struct device_attribute *attr,
+               const char *buf,
+               size_t count)
+{
+       struct drm_device *ddev = dev_get_drvdata(dev);
+       struct amdgpu_device *adev = ddev->dev_private;
+       int ret;
+       uint32_t mask = 0;
+
+       ret = amdgpu_read_mask(buf, count, &mask);
+       if (ret)
+               return ret;
+
        if (adev->powerplay.pp_funcs->force_clock_level)
                amdgpu_dpm_force_clock_level(adev, PP_SCLK, mask);
 
-fail:
        return count;
 }
 
@@ -664,32 +683,15 @@ static ssize_t amdgpu_set_pp_dpm_mclk(struct device *dev,
        struct drm_device *ddev = dev_get_drvdata(dev);
        struct amdgpu_device *adev = ddev->dev_private;
        int ret;
-       long level;
        uint32_t mask = 0;
-       char *sub_str = NULL;
-       char *tmp;
-       char buf_cpy[count];
-       const char delimiter[3] = {' ', '\n', '\0'};
 
-       memcpy(buf_cpy, buf, count+1);
-       tmp = buf_cpy;
-       while (tmp[0]) {
-               sub_str =  strsep(&tmp, delimiter);
-               if (strlen(sub_str)) {
-                       ret = kstrtol(sub_str, 0, &level);
+       ret = amdgpu_read_mask(buf, count, &mask);
+       if (ret)
+               return ret;
 
-                       if (ret) {
-                               count = -EINVAL;
-                               goto fail;
-                       }
-                       mask |= 1 << level;
-               } else
-                       break;
-       }
        if (adev->powerplay.pp_funcs->force_clock_level)
                amdgpu_dpm_force_clock_level(adev, PP_MCLK, mask);
 
-fail:
        return count;
 }
 
@@ -714,33 +716,15 @@ static ssize_t amdgpu_set_pp_dpm_pcie(struct device *dev,
        struct drm_device *ddev = dev_get_drvdata(dev);
        struct amdgpu_device *adev = ddev->dev_private;
        int ret;
-       long level;
        uint32_t mask = 0;
-       char *sub_str = NULL;
-       char *tmp;
-       char buf_cpy[count];
-       const char delimiter[3] = {' ', '\n', '\0'};
-
-       memcpy(buf_cpy, buf, count+1);
-       tmp = buf_cpy;
 
-       while (tmp[0]) {
-               sub_str =  strsep(&tmp, delimiter);
-               if (strlen(sub_str)) {
-                       ret = kstrtol(sub_str, 0, &level);
+       ret = amdgpu_read_mask(buf, count, &mask);
+       if (ret)
+               return ret;
 
-                       if (ret) {
-                               count = -EINVAL;
-                               goto fail;
-                       }
-                       mask |= 1 << level;
-               } else
-                       break;
-       }
        if (adev->powerplay.pp_funcs->force_clock_level)
                amdgpu_dpm_force_clock_level(adev, PP_PCIE, mask);
 
-fail:
        return count;
 }