Catch SGI buffer overruns

python-pillow · Jan 2, 2020 · a79b65c · a79b65c · NicoleG25 · Jan 5, 2020
1 parent 93b22b8
commit a79b65c
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Showing 4 changed files with 19 additions and 6 deletions.
diff --git a/Tests/images/sgi_overrun_expandrow.bin b/Tests/images/sgi_overrun_expandrow.bin
diff --git a/Tests/images/sgi_overrun_expandrow2.bin b/Tests/images/sgi_overrun_expandrow2.bin
diff --git a/Tests/test_image.py b/Tests/test_image.py
@@ -593,6 +593,8 @@ def test_overrun(self):
         for file in [
             "fli_overrun.bin",
             "sgi_overrun.bin",
+            "sgi_overrun_expandrow.bin",
+            "sgi_overrun_expandrow2.bin",
             "pcx_overrun.bin",
             "pcx_overrun2.bin",
         ]:

diff --git a/src/libImaging/SgiRleDecode.c b/src/libImaging/SgiRleDecode.c
@@ -25,7 +25,7 @@ static void read4B(UINT32* dest, UINT8* buf)
     *dest = (UINT32)((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]);
 }
 
-static int expandrow(UINT8* dest, UINT8* src, int n, int z)
+static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
 {
     UINT8 pixel, count;
 
@@ -37,6 +37,9 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z)
         count = pixel & RLE_MAX_RUN;
         if (!count)
             return count;
+        if (count > xsize) {
+            return -1;
+        }
         if (pixel & RLE_COPY_FLAG) {
             while(count--) {
                 *dest = *src++;
@@ -56,7 +59,7 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z)
     return 0;
 }
 
-static int expandrow2(UINT8* dest, const UINT8* src, int n, int z)
+static int expandrow2(UINT8* dest, const UINT8* src, int n, int z, int xsize)
 {
     UINT8 pixel, count;
 
@@ -70,6 +73,9 @@ static int expandrow2(UINT8* dest, const UINT8* src, int n, int z)
         count = pixel & RLE_MAX_RUN;
         if (!count)
             return count;
+        if (count > xsize) {
+            return -1;
+        }
         if (pixel & RLE_COPY_FLAG) {
             while(count--) {
                 memcpy(dest, src, 2);
@@ -96,6 +102,7 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
     UINT8 *ptr;
     SGISTATE *c;
     int err = 0;
+    int status;
 
     /* Get all data from File descriptor */
     c = (SGISTATE*)state->context;
@@ -164,12 +171,16 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
 
             /* row decompression */
             if (c->bpc ==1) {
-                if(expandrow(&state->buffer[c->channo], &ptr[c->rleoffset], c->rlelength, im->bands))
-                    goto sgi_finish_decode;
+                status = expandrow(&state->buffer[c->channo], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize);
             }
             else {
-                if(expandrow2(&state->buffer[c->channo * 2], &ptr[c->rleoffset], c->rlelength, im->bands))
-                    goto sgi_finish_decode;
+                status = expandrow2(&state->buffer[c->channo * 2], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize);
+            }
+            if (status == -1) {
+                state->errcode = IMAGING_CODEC_OVERRUN;
+                return -1;
+            } else if (status == 1) {
+                goto sgi_finish_decode;
             }
 
             state->count += c->rlelength;