Catch buffer overruns

Tests/test_image.py

@@ -589,6 +589,15 @@ def act(fp):
 
             self.assertFalse(fp.closed)
 
+    def test_overrun(self):
+        for file in ["fli_overrun.bin", "sgi_overrun.bin", "pcx_overrun.bin"]:
+            im = Image.open(os.path.join("Tests/images", file))
+            try:
+                im.load()
+                self.assertFail()
+            except IOError as e:
+                self.assertEqual(str(e), "buffer overrun when reading image file")
+
 
 class MockEncoder(object):
     pass

src/libImaging/FliDecode.c

@@ -30,7 +30,7 @@ ImagingFliDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t byt
 {
     UINT8* ptr;
     int framesize;
-    int c, chunks;
+    int c, chunks, advance;
     int l, lines;
     int i, j, x = 0, y, ymax;
 
@@ -59,10 +59,16 @@ ImagingFliDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t byt
 
     chunks = I16(ptr+6);
     ptr += 16;
+    bytes -= 16;
 
     /* Process subchunks */
     for (c = 0; c < chunks; c++) {
-	UINT8 *data = ptr + 6;
+	UINT8* data;
+	if (bytes < 10) {
+	    state->errcode = IMAGING_CODEC_OVERRUN;
+	    return -1;
+	}
+	data = ptr + 6;
 	switch (I16(ptr+4)) {
 	case 4: case 11:
 	    /* FLI COLOR chunk */
@@ -198,7 +204,9 @@ ImagingFliDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t byt
 	    state->errcode = IMAGING_CODEC_UNKNOWN;
 	    return -1;
 	}
-	ptr += I32(ptr);
+	advance = I32(ptr);
+	ptr += advance;
+	bytes -= advance;
     }
 
     return -1; /* end of frame */

src/libImaging/PcxDecode.c

@@ -22,6 +22,11 @@ ImagingPcxDecode(Imaging im, ImagingCodecState state, UINT8* buf, Py_ssize_t byt
     UINT8 n;
     UINT8* ptr;
 
+    if (strcmp(im->mode, "1") == 0 && state->xsize > state->bytes * 8) {
+        state->errcode = IMAGING_CODEC_OVERRUN;
+        return -1;
+    }
+
     ptr = buf;
 
     for (;;) {

src/libImaging/SgiRleDecode.c

@@ -157,6 +157,11 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
             c->rlelength = c->lengthtab[c->rowno + c->channo * im->ysize];
             c->rleoffset -= SGI_HEADER_SIZE;
 
+            if (c->rleoffset + c->rlelength > c->bufsize) {
+                state->errcode = IMAGING_CODEC_OVERRUN;
+                return -1;
+            }
+
             /* row decompression */
             if (c->bpc ==1) {
                 if(expandrow(&state->buffer[c->channo], &ptr[c->rleoffset], c->rlelength, im->bands))