[FFmpeg-devel] [PATCH] avcodec/exif: avoid printing errors for makernote non-IFD parsing (PR #20604)

[Leo Izen via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #20604 opened by Leo Izen (Traneptora)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20604
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20604.patch

When we parse a MakerNote, we first try to parse it as an IFD and if
that fails, we try to re-parse it as a binary blob. This is because
MakerNote is not well-documented in its nature.

However, if we fail to parse it the first time, we should not av_log
error messages about the parse failure, so instead we log these as
AV_LOG_DEBUG.

Signed-off-by: Leo Izen <leo.izen@gmail.com>
Reported-by: Ramiro Polla <ramiro.polla@gmail.com>


>From 5af5f6d7c3253bf51a70645872d1dcc8b5e87d72 Mon Sep 17 00:00:00 2001
From: Leo Izen <leo.izen@gmail.com>
Date: Wed, 24 Sep 2025 20:34:26 -0400
Subject: [PATCH] avcodec/exif: avoid printing errors for makernote non-IFD
 parsing

When we parse a MakerNote, we first try to parse it as an IFD and if
that fails, we try to re-parse it as a binary blob. This is because
MakerNote is not well-documented in its nature.

However, if we fail to parse it the first time, we should not av_log
error messages about the parse failure, so instead we log these as
AV_LOG_DEBUG.

Signed-off-by: Leo Izen <leo.izen@gmail.com>
Reported-by: Ramiro Polla <ramiro.polla@gmail.com>
---
 libavcodec/exif.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/libavcodec/exif.c b/libavcodec/exif.c
index e7aa9b8d8f..877dead0fb 100644
--- a/libavcodec/exif.c
+++ b/libavcodec/exif.c
@@ -453,7 +453,7 @@ static int exif_get_makernote_offset(GetByteContext *gb)
 }
 
 static int exif_parse_ifd_list(void *logctx, GetByteContext *gb, int le,
-                               int depth, AVExifMetadata *ifd);
+                               int depth, AVExifMetadata *ifd, int makernote);
 
 static int exif_decode_tag(void *logctx, GetByteContext *gb, int le,
                            int depth, AVExifEntry *entry)
@@ -504,7 +504,7 @@ static int exif_decode_tag(void *logctx, GetByteContext *gb, int le,
                 return AVERROR(ENOMEM);
             bytestream2_get_buffer(gb, entry->ifd_lead, entry->ifd_offset);
         }
-        ret = exif_parse_ifd_list(logctx, gb, le, depth + 1, &entry->value.ifd);
+        ret = exif_parse_ifd_list(logctx, gb, le, depth + 1, &entry->value.ifd, entry->id == MAKERNOTE_TAG);
         if (ret < 0 && entry->id == MAKERNOTE_TAG) {
             /*
              * we guessed that MakerNote was an IFD
@@ -532,7 +532,7 @@ end:
 }
 
 static int exif_parse_ifd_list(void *logctx, GetByteContext *gb, int le,
-                               int depth, AVExifMetadata *ifd)
+                               int depth, AVExifMetadata *ifd, int makernote)
 {
     uint32_t entries;
     size_t required_size;
@@ -541,18 +541,21 @@ static int exif_parse_ifd_list(void *logctx, GetByteContext *gb, int le,
     av_log(logctx, AV_LOG_DEBUG, "parsing IFD list at offset: %d\n", bytestream2_tell(gb));
 
     if (bytestream2_get_bytes_left(gb) < 2) {
-        av_log(logctx, AV_LOG_ERROR, "not enough bytes remaining in EXIF buffer: 2 required\n");
+        av_log(logctx, makernote ? AV_LOG_DEBUG : AV_LOG_ERROR,
+               "not enough bytes remaining in EXIF buffer: 2 required\n");
         return AVERROR_INVALIDDATA;
     }
 
     entries = ff_tget_short(gb, le);
     if (bytestream2_get_bytes_left(gb) < entries * BASE_TAG_SIZE) {
-        av_log(logctx, AV_LOG_ERROR, "not enough bytes remaining in EXIF buffer. entries: %" PRIu32 "\n", entries);
+        av_log(logctx, makernote ? AV_LOG_DEBUG : AV_LOG_ERROR,
+               "not enough bytes remaining in EXIF buffer. entries: %" PRIu32 "\n", entries);
         return AVERROR_INVALIDDATA;
     }
     if (entries > 4096) {
         /* that is a lot of entries, probably an error */
-        av_log(logctx, AV_LOG_ERROR, "too many entries: %" PRIu32 "\n", entries);
+        av_log(logctx, makernote ? AV_LOG_DEBUG : AV_LOG_ERROR,
+               "too many entries: %" PRIu32 "\n", entries);
         return AVERROR_INVALIDDATA;
     }
 
@@ -811,7 +814,7 @@ int av_exif_parse_buffer(void *logctx, const uint8_t *buf, size_t size,
      * parse IFD0 here. If the return value is positive that tells us
      * there is subimage metadata, but we don't parse that IFD here
      */
-    ret = exif_parse_ifd_list(logctx, &gbytes, le, 0, ifd);
+    ret = exif_parse_ifd_list(logctx, &gbytes, le, 0, ifd, 0);
     if (ret < 0) {
         av_exif_free(ifd);
         av_log(logctx, AV_LOG_ERROR, "error decoding EXIF data: %s\n", av_err2str(ret));
@@ -924,7 +927,7 @@ int avpriv_exif_decode_ifd(void *logctx, const uint8_t *buf, int size,
     GetByteContext gb;
     int ret;
     bytestream2_init(&gb, buf, size);
-    ret = exif_parse_ifd_list(logctx, &gb, le, depth, &ifd);
+    ret = exif_parse_ifd_list(logctx, &gb, le, depth, &ifd, 0);
     if (ret < 0)
         return ret;
     ret = av_exif_ifd_to_dict(logctx, &ifd, metadata);
-- 
2.49.1

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