drm/amdgpu: Prevent shift wrapping in amdgpu_read_mask()

[ Upstream commit c915ef890d5dc79f483e1ca3b3a5b5f1a170690c ]

If the user passes a "level" value which is higher than 31 then that
leads to shift wrapping.  The undefined behavior will lead to a
syzkaller stack dump.

Fixes: 5632708f4452 ("drm/amd/powerplay: add dpm force multiple levels on cz/tonga/fiji/polaris (v2)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 3f744e72912f11b2c4036b7ba053cc78af9f1698..bcb7ab5c602d1dab9d47a27aa1810bbea3590499 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -870,7 +870,7 @@ static ssize_t amdgpu_get_pp_dpm_sclk(struct device *dev,
 static ssize_t amdgpu_read_mask(const char *buf, size_t count, uint32_t *mask)
 {
        int ret;
-       long level;
+       unsigned long level;
        char *sub_str = NULL;
        char *tmp;
        char buf_cpy[AMDGPU_MASK_BUF_MAX + 1];
@@ -886,8 +886,8 @@ static ssize_t amdgpu_read_mask(const char *buf, size_t count, uint32_t *mask)
        while (tmp[0]) {
                sub_str = strsep(&tmp, delimiter);
                if (strlen(sub_str)) {
-                       ret = kstrtol(sub_str, 0, &level);
-                       if (ret)
+                       ret = kstrtoul(sub_str, 0, &level);
+                       if (ret || level > 31)
                                return -EINVAL;
                        *mask |= 1 << level;
                } else