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From:   Kees Cook <keescook@chromium.org>
To:     linux-hardening@vger.kernel.org
Cc:     Kees Cook <keescook@chromium.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Keith Packard <keithpac@amazon.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-staging@lists.linux.dev, linux-block@vger.kernel.org,
        linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: [PATCH 01/64] media: omap3isp: Extract struct group for memcpy() region
Date:   Tue, 27 Jul 2021 13:57:52 -0700
Message-Id: <20210727205855.411487-2-keescook@chromium.org>
In-Reply-To: <20210727205855.411487-1-keescook@chromium.org>
References: <20210727205855.411487-1-keescook@chromium.org>
MIME-Version: 1.0
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In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.  Wrap the target region
in a common named structure. This additionally fixes a theoretical
misalignment of the copy (since the size of "buf" changes between 64-bit
and 32-bit, but this is likely never built for 64-bit).

FWIW, I think this code is totally broken on 64-bit (which appears to
not be a "real" build configuration): it would either always fail (with
an uninitialized data->buf_size) or would cause corruption in userspace
due to the copy_to_user() in the call path against an uninitialized
data->buf value:

omap3isp_stat_request_statistics_time32(...)
    struct omap3isp_stat_data data64;
    ...
    omap3isp_stat_request_statistics(stat, &data64);

int omap3isp_stat_request_statistics(struct ispstat *stat,
                                     struct omap3isp_stat_data *data)
    ...
    buf = isp_stat_buf_get(stat, data);

static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
                                               struct omap3isp_stat_data *data)
...
    if (buf->buf_size > data->buf_size) {
            ...
            return ERR_PTR(-EINVAL);
    }
    ...
    rval = copy_to_user(data->buf,
                        buf->virt_addr,
                        buf->buf_size);

Regardless, additionally initialize data64 to be zero-filled to avoid
undefined behavior.

Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/media/platform/omap3isp/ispstat.c |  5 +--
 include/uapi/linux/omap3isp.h             | 44 +++++++++++++++++------
 2 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
index 5b9b57f4d9bf..ea8222fed38e 100644
--- a/drivers/media/platform/omap3isp/ispstat.c
+++ b/drivers/media/platform/omap3isp/ispstat.c
@@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
 int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
 					struct omap3isp_stat_data_time32 *data)
 {
-	struct omap3isp_stat_data data64;
+	struct omap3isp_stat_data data64 = { };
 	int ret;
 
 	ret = omap3isp_stat_request_statistics(stat, &data64);
@@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
 
 	data->ts.tv_sec = data64.ts.tv_sec;
 	data->ts.tv_usec = data64.ts.tv_usec;
-	memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
+	data->buf = (uintptr_t)data64.buf;
+	memcpy(&data->frame, &data64.buf, sizeof(data->frame));
 
 	return 0;
 }
diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
index 87b55755f4ff..0a16af91621f 100644
--- a/include/uapi/linux/omap3isp.h
+++ b/include/uapi/linux/omap3isp.h
@@ -159,13 +159,25 @@ struct omap3isp_h3a_aewb_config {
 };
 
 /**
- * struct omap3isp_stat_data - Statistic data sent to or received from user
- * @ts: Timestamp of returned framestats.
- * @buf: Pointer to pass to user.
+ * struct omap3isp_stat_frame - Statistic data without timestamp nor pointer.
+ * @buf_size: Size of buffer.
  * @frame_number: Frame number of requested stats.
  * @cur_frame: Current frame number being processed.
  * @config_counter: Number of the configuration associated with the data.
  */
+struct omap3isp_stat_frame {
+	__u32 buf_size;
+	__u16 frame_number;
+	__u16 cur_frame;
+	__u16 config_counter;
+};
+
+/**
+ * struct omap3isp_stat_data - Statistic data sent to or received from user
+ * @ts: Timestamp of returned framestats.
+ * @buf: Pointer to pass to user.
+ * @frame: Statistic data for frame.
+ */
 struct omap3isp_stat_data {
 #ifdef __KERNEL__
 	struct {
@@ -176,10 +188,15 @@ struct omap3isp_stat_data {
 	struct timeval ts;
 #endif
 	void __user *buf;
-	__u32 buf_size;
-	__u16 frame_number;
-	__u16 cur_frame;
-	__u16 config_counter;
+	union {
+		struct {
+			__u32 buf_size;
+			__u16 frame_number;
+			__u16 cur_frame;
+			__u16 config_counter;
+		};
+		struct omap3isp_stat_frame frame;
+	};
 };
 
 #ifdef __KERNEL__
@@ -189,10 +206,15 @@ struct omap3isp_stat_data_time32 {
 		__s32	tv_usec;
 	} ts;
 	__u32 buf;
-	__u32 buf_size;
-	__u16 frame_number;
-	__u16 cur_frame;
-	__u16 config_counter;
+	union {
+		struct {
+			__u32 buf_size;
+			__u16 frame_number;
+			__u16 cur_frame;
+			__u16 config_counter;
+		};
+		struct omap3isp_stat_frame frame;
+	};
 };
 #endif
 
-- 
2.30.2