On Tue, 14 Mar 2023, Jerome Martinez wrote:

Please consider the attached patch.

Before: "Overread buffer. Invalid header?" despite that all bytes are there (the precheck is wrong, not the parsing after the precheck) After: transcoding is fine

A (zeroed) sample file is available at https://trac.ffmpeg.org/ticket/10259

Will apply with a minor fix. Regards, Marton

Jérôme

On 19/10/2022 11:47, Jerome Martinez wrote:

...

stride value is not relevant with unpadded content and the total count of pixels (width x height) must be used instead of the rounding based on width only then multiplied by height

unpadded_10bit value computing is moved sooner in the code in order to be able to use it during computing of minimal content size

Fix 'Overread buffer' error when the content is not lucky enough to have (enough) padding bytes at the end for not being rejected by the formula based on the stride value

Signed-off-by: Jerome Martinez <jerome@mediaarea.net> ---  libavcodec/dpx.c | 34 ++++++++++++++++++----------------  1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/libavcodec/dpx.c b/libavcodec/dpx.c index 4f50608..d4699f6 100644 --- a/libavcodec/dpx.c +++ b/libavcodec/dpx.c @@ -476,14 +476,30 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,          avctx->colorspace = AVCOL_SPC_RGB;      }

+    av_strlcpy(creator, avpkt->data + 160, 100); +    creator[100] = '\0'; +    av_dict_set(&p->metadata, "Creator", creator, 0); + +    av_strlcpy(input_device, avpkt->data + 1556, 32); +    input_device[32] = '\0'; +    av_dict_set(&p->metadata, "Input Device", input_device, 0); + +    // Some devices do not pad 10bit samples to whole 32bit words per row +    if (!memcmp(input_device, "Scanity", 7) || +        !memcmp(creator, "Lasergraphics Inc.", 18)) { +        unpadded_10bit = 1; +    } +      // Table 3c: Runs will always break at scan line boundaries. Packing      // will always break to the next 32-bit word at scan-line boundaries.      // Unfortunately, the encoder produced invalid files, so attempt      // to detect it +    // Also handle special case with unpadded content      need_align = FFALIGN(stride, 4); -    if (need_align*avctx->height + (int64_t)offset > avpkt->size) { +    if (need_align*avctx->height + (int64_t)offset > avpkt->size && +        (!unpadded_10bit || (avctx->width * avctx->height * elements + 2) / 3 * 4 + (int64_t)offset > avpkt->size)) {          // Alignment seems unappliable, try without -        if (stride*avctx->height + (int64_t)offset > avpkt->size) { +        if (stride*avctx->height + (int64_t)offset > avpkt->size || unpadded_10bit) {              av_log(avctx, AV_LOG_ERROR, "Overread buffer. Invalid header?\n");              return AVERROR_INVALIDDATA;          } else { @@ -609,20 +625,6 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,      if ((ret = ff_get_buffer(avctx, p, 0)) < 0)          return ret;

-    av_strlcpy(creator, avpkt->data + 160, 100); -    creator[100] = '\0'; -    av_dict_set(&p->metadata, "Creator", creator, 0); - -    av_strlcpy(input_device, avpkt->data + 1556, 32); -    input_device[32] = '\0'; -    av_dict_set(&p->metadata, "Input Device", input_device, 0); - -    // Some devices do not pad 10bit samples to whole 32bit words per row -    if (!memcmp(input_device, "Scanity", 7) || -        !memcmp(creator, "Lasergraphics Inc.", 18)) { -        unpadded_10bit = 1; -    } -      // Move pointer to offset from start of file      buf =  avpkt->data + offset;