linux-kernel - [PATCH 4.19 098/247] drm/amdgpu: Prevent shift wrapping in amdgpu_read

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Message-Id: <20210301161036.477443445@linuxfoundation.org>
Date:   Mon,  1 Mar 2021 17:11:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 098/247] drm/amdgpu: Prevent shift wrapping in amdgpu_read_mask()

From: Dan Carpenter <dan.carpenter@...cle.com>

[ 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@...cle.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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