CVE-2016-0740 – Buffer overflow in TiffDecode.c

Pillow 3.1.0 and earlier when linked against libtiff >= 4.0.0 on x64 may overflow a buffer when reading a specially crafted tiff file.

Specifically, libtiff >= 4.0.0 changed the return type of TIFFScanlineSize from int32 to machine dependent int32|64. If the scanline is sized so that it overflows an int32, it may be interpreted as a negative number, which will then pass the size check in TiffDecode.c line 236. To do this, the logical scanline size has to be > 2gb, and for the test file, the allocated buffer size is 64k against a roughly 4gb scan line size. Any image data over 64k is written over the heap, causing a segfault.

This issue was found by security researcher FourOne.

CVE-2016-0775 – Buffer overflow in FliDecode.c

In all versions of Pillow, dating back at least to the last PIL 1.1.7 release, FliDecode.c has a buffer overflow error.

Around line 192:

case 16:
    /* COPY chunk */
    for (y = 0; y < state->ysize; y++) {
        UINT8* buf = (UINT8*) im->image[y];
        memcpy(buf+x, data, state->xsize);
        data += state->xsize;

The memcpy has error where x is added to the target buffer address. X is used in several internal temporary variable roles, but can take a value up to the width of the image. Im->image[y] is a set of row pointers to segments of memory that are the size of the row. At the max y, this will write the contents of the line off the end of the memory buffer, causing a segfault.

This issue was found by Alyssa Besseling at Atlassian

CVE-2016-2533 – Buffer overflow in PcdDecode.c

In all versions of Pillow, dating back at least to the last PIL 1.1.7 release, PcdDecode.c has a buffer overflow error.

The state.buffer for PcdDecode.c is allocated based on a 3 bytes per pixel sizing, where PcdDecode.c wrote into the buffer assuming 4 bytes per pixel. This writes 768 bytes beyond the end of the buffer into other Python object storage. In some cases, this causes a segfault, in others an internal Python malloc error.

Integer overflow in Resample.c

If a large value was passed into the new size for an image, it is possible to overflow an int32 value passed into malloc.

kk = malloc(xsize * kmax * sizeof(float)); ... xbounds = malloc(xsize * 2 * sizeof(int));

xsize is trusted user input. These multiplications can overflow, leading the malloc’d buffer to be undersized. These allocations are followed by a loop that writes out of bounds. This can lead to corruption on the heap of the Python process with attacker controlled float data.

This issue was found by Ned Williamson.