media: s5p-jpeg: prevent buffer overflows

commit 14a22762c3daeac59a5a534e124acbb4d7a79b3a upstream.

The current logic allows word to be less than 2. If this happens,
there will be buffer overflows, as reported by smatch. Add extra
checks to prevent it.

While here, remove an unused word = 0 assignment.

Fixes: 6c96dbbc2aa9 ("[media] s5p-jpeg: add support for 5433")
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/platform/samsung/s5p-jpeg/jpeg-core.c b/drivers/media/platform/samsung/s5p-jpeg/jpeg-core.c
index 55814041b8d8f3f6578c9a25bce1f588d94af184..d8d1f17cee83f351f8f69298e9d72e3489b922e8 100644 (file)
--- a/drivers/media/platform/samsung/s5p-jpeg/jpeg-core.c
+++ b/drivers/media/platform/samsung/s5p-jpeg/jpeg-core.c
@@ -775,11 +775,14 @@ static void exynos4_jpeg_parse_decode_h_tbl(struct s5p_jpeg_ctx *ctx)
                (unsigned long)vb2_plane_vaddr(&vb->vb2_buf, 0) + ctx->out_q.sos + 2;
        jpeg_buffer.curr = 0;
 
-       word = 0;
-
        if (get_word_be(&jpeg_buffer, &word))
                return;
-       jpeg_buffer.size = (long)word - 2;
+
+       if (word < 2)
+               jpeg_buffer.size = 0;
+       else
+               jpeg_buffer.size = (long)word - 2;
+
        jpeg_buffer.data += 2;
        jpeg_buffer.curr = 0;
 
@@ -1058,6 +1061,7 @@ static int get_word_be(struct s5p_jpeg_buffer *buf, unsigned int *word)
        if (byte == -1)
                return -1;
        *word = (unsigned int)byte | temp;
+
        return 0;
 }
 
@@ -1145,7 +1149,7 @@ static bool s5p_jpeg_parse_hdr(struct s5p_jpeg_q_data *result,
                        if (get_word_be(&jpeg_buffer, &word))
                                break;
                        length = (long)word - 2;
-                       if (!length)
+                       if (length <= 0)
                                return false;
                        sof = jpeg_buffer.curr; /* after 0xffc0 */
                        sof_len = length;
@@ -1176,7 +1180,7 @@ static bool s5p_jpeg_parse_hdr(struct s5p_jpeg_q_data *result,
                        if (get_word_be(&jpeg_buffer, &word))
                                break;
                        length = (long)word - 2;
-                       if (!length)
+                       if (length <= 0)
                                return false;
                        if (n_dqt >= S5P_JPEG_MAX_MARKER)
                                return false;
@@ -1189,7 +1193,7 @@ static bool s5p_jpeg_parse_hdr(struct s5p_jpeg_q_data *result,
                        if (get_word_be(&jpeg_buffer, &word))
                                break;
                        length = (long)word - 2;
-                       if (!length)
+                       if (length <= 0)
                                return false;
                        if (n_dht >= S5P_JPEG_MAX_MARKER)
                                return false;
@@ -1214,6 +1218,7 @@ static bool s5p_jpeg_parse_hdr(struct s5p_jpeg_q_data *result,
                        if (get_word_be(&jpeg_buffer, &word))
                                break;
                        length = (long)word - 2;
+                       /* No need to check underflows as skip() does it  */
                        skip(&jpeg_buffer, length);
                        break;
                }