fix: various protections against corrupted files

Fixes 3952

Several interrelated fixes to guard against corrupted files:

* Extend the `limits:max_imagesize_MB` sanity check to Targa files to
  address 3952 specifically, and check in that failing example file
  into the testsuite. (N.B.: Only a couple readers use this, TIFF and
  now Targa. it should be extended to the others. Mackerel!)

* Improve the error message used for the above, both for Targa and
  TIFF.

* For low-memory situations, perhaps the default of 32GB is too large.
  Make the default be the minimum of 32GB and 1/2 the size of physical
  memory on the machine. (An app that legit expects humongous files is
  expected to raise the limit appropriately.)

* The generic "Read error: hit end of file" we sometimes issued from
  `ImageInput::ioread()` was hard to discern which reader it came
  from, in cases where the file extension was absent or misleading and
  a succession of files were tried. By changing this error message to
  say which format reader triggered the error, it might make these
  errors easier to track down in the future. This also changed the
  reference output of a few test involving truncated or corrupted
  files.

Signed-off-by: Larry Gritz <[email protected]>

src/include/OpenImageIO/imageio.h

@@ -2895,12 +2895,14 @@ OIIO_API std::string geterror(bool clear = true);
 ///
 /// - `int limits:imagesize_MB` (32768)
 ///
-///    When nonzero, the maximum size in MB of the uncompressed pixel data of
-///    a single 2D image. Images whose headers indicate that they are larger
-///    than this might be assumed to be corrupted or malicious files. The
-///    default is 32768 (32 GB of uncompressed pixel data -- equivalent to 64k
-///    x 64k x 4 channel x half). In situations when images larger than this
-///    are expected to be encountered, you should raise this limit.
+///    When nonzero, the maximum expected size in MB of the uncompressed pixel
+///    data of a single 2D image. Images whose headers indicate that they are
+///    larger than this might be assumed to be corrupted or malicious files.
+///    The default is 32768 (32 GB of uncompressed pixel data -- equivalent to
+///    64k x 64k x 4 channel x half), or half the amount of total physical
+///    memory available to the running process, whichever is smaller. In
+///    situations when images larger than this are expected to be encountered,
+///    you should raise this limit.
 ///
 /// - `int log_times`
 ///

src/libOpenImageIO/imageinput.cpp

@@ -1249,7 +1249,8 @@ ImageInput::ioread(void* buf, size_t itemsize, size_t nitems)
     size_t n    = m_io->read(buf, size);
     if (n != size) {
         if (size_t(m_io->tell()) >= m_io->size())
-            ImageInput::errorfmt("Read error: hit end of file");
+            ImageInput::errorfmt("Read error: hit end of file in {} reader",
+                                 format_name());
         else
             ImageInput::errorfmt(
                 "Read error at position {}, could only read {}/{} bytes {}",

src/libOpenImageIO/imageio.cpp

@@ -46,7 +46,8 @@ int tiff_half(0);
 int tiff_multithread(1);
 int dds_bc5normal(0);
 int limit_channels(1024);
-int limit_imagesize_MB(32 * 1024);
+int limit_imagesize_MB(std::min(32 * 1024,
+                                int((Sysutil::physical_memory() / 2) >> 20)));
 ustring font_searchpath(Sysutil::getenv("OPENIMAGEIO_FONTS"));
 ustring plugin_searchpath(OIIO_DEFAULT_PLUGIN_SEARCHPATH);
 std::string format_list;         // comma-separated list of all formats

src/targa.imageio/targainput.cpp

@@ -15,6 +15,7 @@
 #include <OpenImageIO/sysutil.h>
 #include <OpenImageIO/typedesc.h>
 
+#include "imageio_pvt.h"
 #include "targa_pvt.h"
 
 OIIO_PLUGIN_NAMESPACE_BEGIN
@@ -285,6 +286,19 @@ TGAInput::open(const std::string& name, ImageSpec& newspec)
     }
     m_spec.attribute("targa:version", int(m_tga_version));
 
+    if (pvt::limit_imagesize_MB
+        && m_spec.image_bytes(true)
+               > pvt::limit_imagesize_MB * imagesize_t(1024 * 1024)) {
+        errorfmt(
+            "Uncompressed image size {:.1f} MB exceeds the {} MB limit.\n"
+            "Image claimed to be {}x{}, {}-channel {}. Possible corrupt input?\n"
+            "If this is a valid file, raise the OIIO attribute \"limits:imagesize_MB\".",
+            float(m_spec.image_bytes(true)) / float(1024 * 1024),
+            pvt::limit_imagesize_MB, m_spec.width, m_spec.height,
+            m_spec.nchannels, m_spec.format);
+        return false;
+    }
+
     if (m_spec.alpha_channel != -1 && m_alpha_type == TGA_ALPHA_USEFUL
         && m_keep_unassociated_alpha)
         m_spec.attribute("oiio:UnassociatedAlpha", 1);

src/tiff.imageio/tiffinput.cpp

@@ -849,9 +849,12 @@ TIFFInput::seek_subimage(int subimage, int miplevel)
             && m_spec.image_bytes(true)
                    > pvt::limit_imagesize_MB * imagesize_t(1024 * 1024)) {
             errorfmt(
-                "Uncompressed image size {:.1f} MB exceeds \"limits:imagesize_MB\" = {}. Possible corrupt input?\nIf you're sure this is a valid file, raise the OIIO global attribute \"limits:imagesize_MB\".",
+                "Uncompressed image size {:.1f} MB exceeds the {} MB limit.\n"
+                "Image claimed to be {}x{}, {}-channel {}. Possible corrupt input?\n"
+                "If this is a valid file, raise the OIIO attribute \"limits:imagesize_MB\".",
                 float(m_spec.image_bytes(true)) / float(1024 * 1024),
-                pvt::limit_imagesize_MB);
+                pvt::limit_imagesize_MB, m_spec.width, m_spec.height,
+                m_spec.nchannels, m_spec.format);
             return false;
         }
         return true;

testsuite/dds/ref/out.txt

@@ -184,7 +184,7 @@ Reading ../oiio-images/dds/broken/dds_bc3_just_header.dds
     channel list: R, G, B, A
     compression: "DXT5"
     textureformat: "Plain Texture"
-oiiotool ERROR: read : "../oiio-images/dds/broken/dds_bc3_no_full_header.dds": Read error: hit end of file
+oiiotool ERROR: read : "../oiio-images/dds/broken/dds_bc3_no_full_header.dds": Read error: hit end of file in dds reader
 Full command line was:
 > oiiotool --info -v -a --hash ../oiio-images/dds/broken/dds_bc3_no_full_header.dds
 Reading ../oiio-images/dds/broken/dds_bc7_just_header.dds

testsuite/png-damaged/ref/out.txt

@@ -1,11 +1,11 @@
-libpng error: IDAT: Read error: hit end of file
+libpng error: IDAT: Read error: hit end of file in png reader
 iconvert ERROR copying "../oiio-images/png/broken/invalid_gray_alpha_sbit.png" to "invalid_gray_alpha_sbit.png" :
-	Read error: hit end of file
-PNG read error: IDAT: Read error: hit end of file
+	Read error: hit end of file in png reader
+PNG read error: IDAT: Read error: hit end of file in png reader
 libpng error: No IDATs written into file
 Comparing "../oiio-images/png/broken/invalid_gray_alpha_sbit.png" and "invalid_gray_alpha_sbit.png"
-libpng error: tEXt: Read error: hit end of file
-libpng error: tEXt: Read error: hit end of file
+libpng error: tEXt: Read error: hit end of file in png reader
+libpng error: tEXt: Read error: hit end of file in png reader
 idiff ERROR: Could not read invalid_gray_alpha_sbit.png:
-	Invalid image file "invalid_gray_alpha_sbit.png": Read error: hit end of file
-PNG read error: tEXt: Read error: hit end of file
+	Invalid image file "invalid_gray_alpha_sbit.png": Read error: hit end of file in png reader
+PNG read error: tEXt: Read error: hit end of file in png reader

testsuite/targa/ref/out.txt

@@ -188,22 +188,27 @@ Comparing "../oiio-images/targa/round_grill.tga" and "round_grill.tga"
 PASS
 Converting src/crash1.tga to crash1.exr
 iconvert ERROR copying "src/crash1.tga" to "crash1.exr" :
-	Read error: hit end of file
+	Read error: hit end of file in targa reader
 oiiotool ERROR: read : "src/crash2.tga": Palette image with no palette
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 src/crash2.tga -o crash2.exr
 oiiotool ERROR: read : "src/crash3.tga": Palette image with no palette
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 src/crash3.tga -o crash3.exr
-oiiotool ERROR: read : "src/crash6.tga": Read error: hit end of file
+oiiotool ERROR: read : "src/crash6.tga": Read error: hit end of file in targa reader
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 src/crash6.tga -o crash6.exr
 oiiotool ERROR: read : "src/crash1707.tga": Invalid alpha type 138. Corrupted header?
 Full command line was:
 > oiiotool --oiioattrib try_all_readers 0 src/crash1707.tga -o crash1707.exr
 oiiotool ERROR: read : "src/crash1708.tga": Corrupt palette index
 Full command line was:
-> oiiotool --oiioattrib try_all_readers 0 src/crash1708.tga -o crash1707.exr
+> oiiotool --oiioattrib try_all_readers 0 src/crash1708.tga -o crash1708.exr
+oiiotool ERROR: read : "src/crash3952.tga": Uncompressed image size 15231.5 MB exceeds the 1024 MB limit.
+Image claimed to be 60927x65535, 4-channel uint8. Possible corrupt input?
+If this is a valid file, raise the OIIO attribute "limits:imagesize_MB".
+Full command line was:
+> oiiotool --oiioattrib limits:imagesize_MB 1024 --oiioattrib try_all_readers 0 src/crash3952.tga -o crash3952.exr
 Reading src/1x1.tga
 src/1x1.tga          :    1 x    1, 3 channel, uint2 targa
     SHA-1: DB9237F28F9622F7B7E73B783A8822B63BDB3708

testsuite/targa/run.py

@@ -23,7 +23,10 @@
 command += oiiotool("--oiioattrib try_all_readers 0 src/crash5.tga -o crash5.exr", failureok = True)
 command += oiiotool("--oiioattrib try_all_readers 0 src/crash6.tga -o crash6.exr", failureok = True)
 command += oiiotool("--oiioattrib try_all_readers 0 src/crash1707.tga -o crash1707.exr", failureok = True)
-command += oiiotool("--oiioattrib try_all_readers 0 src/crash1708.tga -o crash1707.exr", failureok = True)
+command += oiiotool("--oiioattrib try_all_readers 0 src/crash1708.tga -o crash1708.exr", failureok = True)
+command += oiiotool("--oiioattrib limits:imagesize_MB 1024 "
+                    "--oiioattrib try_all_readers 0 "
+                    "src/crash3952.tga -o crash3952.exr", failureok = True)
 
 # Test odds and ends, unusual files
 command += rw_command("src", "1x1.tga")