[FFmpeg-cvslog] avformat/jpegxl_probe: check length instead of blindly reading

[Michael Niedermayer]

ffmpeg | branch: release/5.1 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jun  8 10:26:34 2023 -0400| [55de397fe048f5ae2d7ce1f5c630c513f0ff5e05] | committer: Michael Niedermayer

avformat/jpegxl_probe: check length instead of blindly reading

Enable the checked bitreader to avoid overread.
Also add a few checks in loops and between blocks so we exit instead of continued
execution.
Alternatively we could add manual checks so that no overread can happen. This would be
slightly faster but a bit more work and a bit more fragile

Fixes: Out of array accesses
Fixes: 59640/clusterfuzz-testcase-minimized-ffmpeg_dem_JPEGXL_ANIM_fuzzer-6584117345779712

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 1ec4553e355039ce69abf8e49389fa43f1f55fc5)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=55de397fe048f5ae2d7ce1f5c630c513f0ff5e05
---

 libavformat/jpegxl_probe.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/libavformat/jpegxl_probe.c b/libavformat/jpegxl_probe.c
index 45f464ffaf..47c6c54ff4 100644
--- a/libavformat/jpegxl_probe.c
+++ b/libavformat/jpegxl_probe.c
@@ -21,6 +21,7 @@
 
 #include "jpegxl_probe.h"
 
+#define UNCHECKED_BITSTREAM_READER 0
 #define BITSTREAM_READER_LE
 #include "libavcodec/get_bits.h"
 
@@ -292,6 +293,8 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
             skip_bits_long(gb, 1);
         }
     }
+    if (get_bits_left(gb) < 1)
+        return AVERROR_INVALIDDATA;
 
     if (!all_default) {
         jpegxl_skip_bit_depth(gb);
@@ -306,6 +309,8 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
         for (uint32_t i = 0; i < num_extra_channels; i++) {
             if (jpegxl_read_extra_channel_info(gb) < 0)
                 return -1;
+            if (get_bits_left(gb) < 1)
+                return AVERROR_INVALIDDATA;
         }
 
         xyb_encoded = get_bits1(gb);
@@ -335,8 +340,11 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
                             return -1;
                         if (primaries == FF_JPEGXL_PR_CUSTOM) {
                             /* ux/uy values for r,g,b */
-                            for (int i = 0; i < 6; i++)
+                            for (int i = 0; i < 6; i++) {
                                 jxl_u32(gb, 0, 524288, 1048576, 2097152, 19, 19, 20, 21);
+                                if (get_bits_left(gb) < 1)
+                                    return AVERROR_INVALIDDATA;
+                            }
                         }
                     }
                 }
@@ -362,10 +370,14 @@ int ff_jpegxl_verify_codestream_header(const uint8_t *buf, int buflen)
             skip_bits_long(gb, 16 + 16 + 1 + 16);
 
         extensions = jpegxl_u64(gb);
+        if (get_bits_left(gb) < 1)
+            return AVERROR_INVALIDDATA;
         if (extensions) {
             for (int i = 0; i < 64; i++) {
                 if (extensions & (UINT64_C(1) << i))
                     jpegxl_u64(gb);
+                if (get_bits_left(gb) < 1)
+                    return AVERROR_INVALIDDATA;
             }
         }
     }