diff -rupN --no-dereference Pillow-7.2.0/src/libImaging/SgiRleDecode.c Pillow-7.2.0-new/src/libImaging/SgiRleDecode.c

--- Pillow-7.2.0/src/libImaging/SgiRleDecode.c	2021-07-24 22:47:22.782180847 +0200

+++ Pillow-7.2.0-new/src/libImaging/SgiRleDecode.c	2021-07-24 22:47:23.606245817 +0200

@@ -25,13 +25,58 @@ static void read4B(UINT32* dest, UINT8*

     *dest = (UINT32)((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]);

 }

-static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)

+/*

+   SgiRleDecoding is done in a single channel row oriented set of RLE chunks.

+

+   * The file is arranged as

+     - SGI Header

+     - Rle Offset Table

+     - Rle Length Table

+     - Scanline Data

+

+   * Each RLE atom is c->bpc bytes wide (1 or 2)

+

+   * Each RLE Chunk is [specifier atom] [ 1 or n data atoms ]

+

+   * Copy Atoms are a byte with the high bit set, and the low 7 are

+     the number of bytes to copy from the source to the

+     destination. e.g.

+

+         CBBBBBBBB or 0CHLHLHLHLHLHL   (B=byte, H/L = Hi low bytes)

+

+   * Run atoms do not have the high bit set, and the low 7 bits are

+     the number of copies of the next atom to copy to the

+     destination. e.g.:

+

+         RB -> BBBBB or RHL -> HLHLHLHLHL

+

+   The upshot of this is, there is no way to determine the required

+   length of the input buffer from reloffset and rlelength without

+   going through the data at that scan line.

+

+   Furthermore, there's no requirement that individual scan lines

+   pointed to from the rleoffset table are in any sort of order or

+   used only once, or even disjoint. There's also no requirement that

+   all of the data in the scan line area of the image file be used

+

+*/

+static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize, UINT8 *end_of_buffer)

 {

+    /*

+     * n here is the number of rlechunks

+     * z is the number of channels, for calculating the interleave

+     *   offset to go to RGBA style pixels

+     * xsize is the row width

+     * end_of_buffer is the address of the end of the input buffer

+     */

     UINT8 pixel, count;

     int x = 0;

     for (;n > 0; n--)

     {

+        if (src > end_of_buffer) {

+            return -1;

+        }

         pixel = *src++;

         if (n == 1 && pixel != 0) {

             return n;

@@ -45,6 +90,9 @@ static int expandrow(UINT8* dest, UINT8*

         }

         x += count;

         if (pixel & RLE_COPY_FLAG) {

+            if (src + count > end_of_buffer) {

+                return -1;

+            }

             while(count--) {

                 *dest = *src++;

                 dest += z;

@@ -52,6 +100,9 @@ static int expandrow(UINT8* dest, UINT8*

         }

         else {

+            if (src > end_of_buffer) {

+                return -1;

+            }

             pixel = *src++;

             while (count--) {

                 *dest = pixel;

@@ -63,7 +114,7 @@ static int expandrow(UINT8* dest, UINT8*

     return 0;

 }

-static int expandrow2(UINT8* dest, const UINT8* src, int n, int z, int xsize)

+static int expandrow2(UINT8* dest, const UINT8* src, int n, int z, int xsize, UINT8 *end_of_buffer)

 {

     UINT8 pixel, count;

@@ -71,6 +122,9 @@ static int expandrow2(UINT8* dest, const

     for (;n > 0; n--)

     {

+        if (src + 1 > end_of_buffer) {

+            return -1;

+        }

         pixel = src[1];

         src+=2;

         if (n == 1 && pixel != 0) {

@@ -85,6 +139,9 @@ static int expandrow2(UINT8* dest, const

         }

         x += count;

         if (pixel & RLE_COPY_FLAG) {

+            if (src + 2 * count > end_of_buffer) {

+                return -1;

+            }

             while(count--) {

                 memcpy(dest, src, 2);

                 src += 2;

@@ -92,6 +149,9 @@ static int expandrow2(UINT8* dest, const

             }

         }

         else {

+            if (src + 2 > end_of_buffer) {

+                return -1;

+            }

             while (count--) {

                 memcpy(dest, src, 2);

                 dest += z * 2;

@@ -141,7 +201,10 @@ ImagingSgiRleDecode(Imaging im, ImagingC

         return -1;

     }

     _imaging_seek_pyFd(state->fd, SGI_HEADER_SIZE, SEEK_SET);

-    _imaging_read_pyFd(state->fd, (char*)ptr, c->bufsize);

+    if (_imaging_read_pyFd(state->fd, (char *)ptr, c->bufsize) != c->bufsize) {

+        state->errcode = IMAGING_CODEC_UNKNOWN;

+        return -1;

+    }

     /* decoder initialization */

@@ -175,8 +238,6 @@ ImagingSgiRleDecode(Imaging im, ImagingC

         read4B(&c->lengthtab[c->tabindex], &ptr[c->bufindex]);

     }

-    state->count += c->tablen * sizeof(UINT32) * 2;

-

     /* read compressed rows */

     for (c->rowno = 0; c->rowno < im->ysize; c->rowno++, state->y += state->ystep)

     {

@@ -184,19 +245,21 @@ ImagingSgiRleDecode(Imaging im, ImagingC

         {

             c->rleoffset = c->starttab[c->rowno + c->channo * im->ysize];

             c->rlelength = c->lengthtab[c->rowno + c->channo * im->ysize];

-            c->rleoffset -= SGI_HEADER_SIZE;

-            if (c->rleoffset + c->rlelength > c->bufsize) {

+            // Check for underflow of rleoffset-SGI_HEADER_SIZE

+            if (c->rleoffset < SGI_HEADER_SIZE) {

                 state->errcode = IMAGING_CODEC_OVERRUN;

                 goto sgi_finish_decode;

             }

+            c->rleoffset -= SGI_HEADER_SIZE;

+

             /* row decompression */

             if (c->bpc ==1) {

-                status = expandrow(&state->buffer[c->channo], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize);

+                status = expandrow(&state->buffer[c->channo], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize, &ptr[c->bufsize-1]);

             }

             else {

-                status = expandrow2(&state->buffer[c->channo * 2], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize);

+                status = expandrow2(&state->buffer[c->channo * 2], &ptr[c->rleoffset], c->rlelength, im->bands, im->xsize, &ptr[c->bufsize-1]);

             }

             if (status == -1) {

                 state->errcode = IMAGING_CODEC_OVERRUN;

@@ -205,7 +268,6 @@ ImagingSgiRleDecode(Imaging im, ImagingC

                 goto sgi_finish_decode;

             }

-            state->count += c->rlelength;

         }

         /* store decompressed data in image */

@@ -213,7 +275,6 @@ ImagingSgiRleDecode(Imaging im, ImagingC

     }

-    c->bufsize++;

 sgi_finish_decode: ;

@@ -224,5 +285,5 @@ sgi_finish_decode: ;

         state->errcode=err;

         return -1;

     }

-    return state->count - c->bufsize;

+    return 0;

 }

diff -rupN --no-dereference Pillow-7.2.0/Tests/test_sgi_crash.py Pillow-7.2.0-new/Tests/test_sgi_crash.py

--- Pillow-7.2.0/Tests/test_sgi_crash.py	2021-07-24 22:47:22.783180926 +0200

+++ Pillow-7.2.0-new/Tests/test_sgi_crash.py	2021-07-24 22:47:23.606245817 +0200

@@ -10,6 +10,13 @@ from PIL import Image

         "Tests/images/sgi_crash.bin",

         "Tests/images/crash-6b7f2244da6d0ae297ee0754a424213444e92778.sgi",

         "Tests/images/ossfuzz-5730089102868480.sgi",

+        "Tests/images/crash-754d9c7ec485ffb76a90eeaab191ef69a2a3a3cd.sgi",

+        "Tests/images/crash-465703f71a0f0094873a3e0e82c9f798161171b8.sgi",

+        "Tests/images/crash-64834657ee604b8797bf99eac6a194c124a9a8ba.sgi",

+        "Tests/images/crash-abcf1c97b8fe42a6c68f1fb0b978530c98d57ced.sgi",

+        "Tests/images/crash-b82e64d4f3f76d7465b6af535283029eda211259.sgi",

+        "Tests/images/crash-c1b2595b8b0b92cc5f38b6635e98e3a119ade807.sgi",

+        "Tests/images/crash-db8bfa78b19721225425530c5946217720d7df4e.sgi",

     ],

 )

 def test_crashes(test_file):