From 284ae90ae567de4ca53a3f32b472096f0da573a5 Mon Sep 17 00:00:00 2001
From: Su Laus <sulau@freenet.de>
Date: Sun, 5 Nov 2023 03:50:21 +0800
Subject: [PATCH 1/2] Prevent some out-of-memory attacks

Some small fuzzer files fake large amounts of data and provoke out-of-memory situations. For non-compressed data content / tags, out-of-memory can be prevented by comparing with the file size.

At image reading, data size of some tags / data structures (StripByteCounts, StripOffsets, StripArray, TIFF directory) is compared with file size to prevent provoked out-of-memory attacks.

See issue https://gitlab.com/libtiff/libtiff/-/issues/614#note_1602683857
---
 libtiff/tif_dirread.c | 94 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 90 insertions(+), 4 deletions(-)

diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index a762c67..2428257 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -866,8 +866,23 @@ static enum TIFFReadDirEntryErr TIFFReadDirEntryArrayWithLimit(
 	datasize=(*count)*typesize;
 	assert((tmsize_t)datasize>0);
 
-	if( isMapped(tif) && datasize > (uint64_t)tif->tif_size )
-		return TIFFReadDirEntryErrIo;
+    /* Before allocating a huge amount of memory for corrupted files, check if
+     * size of requested memory is not greater than file size.
+     */
+    uint64_t filesize = TIFFGetFileSize(tif);
+    if (datasize > filesize)
+    {
+        TIFFWarningExt(tif->tif_clientdata, "ReadDirEntryArray",
+                        "Requested memory size for tag %d (0x%x) %" PRIu32
+                        " is greather than filesize %" PRIu64
+                        ". Memory not allocated, tag not read",
+                        direntry->tdir_tag, direntry->tdir_tag, datasize,
+                        filesize);
+        return (TIFFReadDirEntryErrAlloc);
+    }
+
+    if (isMapped(tif) && datasize > (uint64_t)tif->tif_size)
+        return TIFFReadDirEntryErrIo;
 
 	if( !isMapped(tif) &&
 		(((tif->tif_flags&TIFF_BIGTIFF) && datasize > 8) ||
@@ -4592,6 +4607,19 @@ EstimateStripByteCounts(TIFF* tif, TIFFDirEntry* dir, uint16_t dircount)
         if( !_TIFFFillStrilesInternal( tif, 0 ) )
             return -1;
 
+    /* Before allocating a huge amount of memory for corrupted files, check if
+     * size of requested memory is not greater than file size. */
+    uint64_t filesize = TIFFGetFileSize(tif);
+    uint64_t allocsize = (uint64_t)td->td_nstrips * sizeof(uint64_t);
+    if (allocsize > filesize)
+    {
+        TIFFWarningExt(tif->tif_clientdata, module,
+                        "Requested memory size for StripByteCounts of %" PRIu64
+                        " is greather than filesize %" PRIu64
+                        ". Memory not allocated",
+                        allocsize, filesize);
+        return -1;
+    }
 	if (td->td_stripbytecount_p)
 		_TIFFfree(td->td_stripbytecount_p);
 	td->td_stripbytecount_p = (uint64_t*)
@@ -4602,9 +4630,7 @@ EstimateStripByteCounts(TIFF* tif, TIFFDirEntry* dir, uint16_t dircount)
 
 	if (td->td_compression != COMPRESSION_NONE) {
 		uint64_t space;
-		uint64_t filesize;
 		uint16_t n;
-		filesize = TIFFGetFileSize(tif);
 		if (!(tif->tif_flags&TIFF_BIGTIFF))
 			space=sizeof(TIFFHeaderClassic)+2+dircount*12+4;
 		else
@@ -4912,6 +4938,20 @@ TIFFFetchDirectory(TIFF* tif, uint64_t diroff, TIFFDirEntry** pdir,
 			dircount16 = (uint16_t)dircount64;
 			dirsize = 20;
 		}
+        /* Before allocating a huge amount of memory for corrupted files, check
+         * if size of requested memory is not greater than file size. */
+        uint64_t filesize = TIFFGetFileSize(tif);
+        uint64_t allocsize = (uint64_t)dircount16 * dirsize;
+        if (allocsize > filesize)
+        {
+            TIFFWarningExt(
+                tif->tif_clientdata, module,
+                "Requested memory size for TIFF directory of %" PRIu64
+                " is greather than filesize %" PRIu64
+                ". Memory not allocated, TIFF directory not read",
+                allocsize, filesize);
+            return 0;
+        }
 		origdir = _TIFFCheckMalloc(tif, dircount16,
 		    dirsize, "to read TIFF directory");
 		if (origdir == NULL)
@@ -5015,6 +5055,20 @@ TIFFFetchDirectory(TIFF* tif, uint64_t diroff, TIFFDirEntry** pdir,
 			             "Sanity check on directory count failed, zero tag directories not supported");
 			return 0;
 		}
+        /* Before allocating a huge amount of memory for corrupted files, check
+         * if size of requested memory is not greater than file size. */
+        uint64_t filesize = TIFFGetFileSize(tif);
+        uint64_t allocsize = (uint64_t)dircount16 * dirsize;
+        if (allocsize > filesize)
+        {
+            TIFFWarningExt(
+                tif->tif_clientdata, module,
+                "Requested memory size for TIFF directory of %" PRIu64
+                " is greather than filesize %" PRIu64
+                ". Memory not allocated, TIFF directory not read",
+                allocsize, filesize);
+            return 0;
+        }
 		origdir = _TIFFCheckMalloc(tif, dircount16,
 						dirsize,
 						"to read TIFF directory");
@@ -5058,6 +5112,8 @@ TIFFFetchDirectory(TIFF* tif, uint64_t diroff, TIFFDirEntry** pdir,
 			}
 		}
 	}
+    /* No check against filesize needed here because "dir" should have same size
+     * than "origdir" checked above. */
 	dir = (TIFFDirEntry*)_TIFFCheckMalloc(tif, dircount16,
 						sizeof(TIFFDirEntry),
 						"to read TIFF directory");
@@ -5852,6 +5908,20 @@ TIFFFetchStripThing(TIFF* tif, TIFFDirEntry* dir, uint32_t nstrips, uint64_t** l
 			return(0);
 		}
 
+        /* Before allocating a huge amount of memory for corrupted files, check
+         * if size of requested memory is not greater than file size. */
+        uint64_t filesize = TIFFGetFileSize(tif);
+        uint64_t allocsize = (uint64_t)nstrips * sizeof(uint64_t);
+        if (allocsize > filesize)
+        {
+            TIFFWarningExt(tif->tif_clientdata, module,
+                            "Requested memory size for StripArray of %" PRIu64
+                            " is greather than filesize %" PRIu64
+                            ". Memory not allocated",
+                            allocsize, filesize);
+            _TIFFfree(data);
+            return (0);
+        }
 		resizeddata=(uint64_t*)_TIFFCheckMalloc(tif, nstrips, sizeof(uint64_t), "for strip array");
 		if (resizeddata==0) {
 			_TIFFfree(data);
@@ -5947,6 +6017,22 @@ static void allocChoppedUpStripArrays(TIFF* tif, uint32_t nstrips,
     }
     bytecount = last_offset + last_bytecount - offset;
 
+    /* Before allocating a huge amount of memory for corrupted files, check if
+     * size of StripByteCount and StripOffset tags is not greater than
+     * file size.
+     */
+    uint64_t allocsize = (uint64_t)nstrips * sizeof(uint64_t) * 2;
+    uint64_t filesize = TIFFGetFileSize(tif);
+    if (allocsize > filesize)
+    {
+        TIFFWarningExt(tif->tif_clientdata, "allocChoppedUpStripArrays",
+                        "Requested memory size for StripByteCount and "
+                        "StripOffsets %" PRIu64
+                        " is greather than filesize %" PRIu64
+                        ". Memory not allocated",
+                        allocsize, filesize);
+        return;
+    }
     newcounts = (uint64_t*) _TIFFCheckMalloc(tif, nstrips, sizeof (uint64_t),
                                              "for chopped \"StripByteCounts\" array");
     newoffsets = (uint64_t*) _TIFFCheckMalloc(tif, nstrips, sizeof (uint64_t),
-- 
2.33.0

