[PATCH 4.19 098/247] drm/amdgpu: Prevent shift wrapping in amdgpu_read_mask()

From: Greg Kroah-Hartman
Date: Mon Mar 01 2021 - 15:39:35 EST


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index e63a253eb4255..cbb969a870f6a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -617,7 +617,7 @@ 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];
@@ -633,8 +633,8 @@ 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
--
2.27.0