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python-pillow/SOURCES/CVE-2021-25293.patch

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From 1312c5426e7dd84e396ef2ff35aa09b64d92d382 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Fri, 9 Apr 2021 19:33:55 +0200
Subject: [PATCH 3/4] CVE-2021-25293
---
src/libImaging/SgiRleDecode.c | 88 +++++++++++++++++++++++++++++------
1 file changed, 75 insertions(+), 13 deletions(-)
diff --git a/src/libImaging/SgiRleDecode.c b/src/libImaging/SgiRleDecode.c
index 2259159..85af456 100644
--- a/src/libImaging/SgiRleDecode.c
+++ b/src/libImaging/SgiRleDecode.c
@@ -25,13 +25,60 @@ 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, 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;
@@ -43,6 +90,9 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
}
x += count;
if (pixel & RLE_COPY_FLAG) {
+ if (src + count > end_of_buffer) {
+ return -1;
+ }
while(count--) {
*dest = *src++;
dest += z;
@@ -50,6 +100,9 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
}
else {
+ if (src > end_of_buffer) {
+ return -1;
+ }
pixel = *src++;
while (count--) {
*dest = pixel;
@@ -61,7 +114,7 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
return 0;
}
-static int expandrow2(UINT16* dest, UINT16* src, int n, int z, int xsize)
+static int expandrow2(UINT16* dest, UINT16* src, int n, int z, int xsize, UINT8 *end_of_buffer)
{
UINT8 pixel, count;
@@ -69,6 +122,9 @@ static int expandrow2(UINT16* dest, UINT16* src, int n, int z, int xsize)
for (;n > 0; n--)
{
+ if (src + 1 > end_of_buffer) {
+ return -1;
+ }
pixel = ((UINT8*)src)[1];
++src;
if (n == 1 && pixel != 0)
@@ -81,12 +137,18 @@ static int expandrow2(UINT16* dest, UINT16* src, int n, int z, int xsize)
}
x += count;
if (pixel & RLE_COPY_FLAG) {
+ if (src + 2 * count > end_of_buffer) {
+ return -1;
+ }
while(count--) {
*dest = *src++;
dest += z;
}
}
else {
+ if (src + 2 > end_of_buffer) {
+ return -1;
+ }
while (count--) {
*dest = *src;
dest += z;
@@ -136,8 +198,10 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
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 */
state->count = 0;
@@ -168,8 +232,6 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
for (c->tabindex = 0, c->bufindex = c->tablen * sizeof(UINT32); c->tabindex < c->tablen; c->tabindex++, c->bufindex+=4)
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)
{
@@ -177,19 +239,21 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
{
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;
@@ -198,7 +262,6 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
goto sgi_finish_decode;
}
- state->count += c->rlelength;
}
/* store decompressed data in image */
@@ -206,7 +269,6 @@ ImagingSgiRleDecode(Imaging im, ImagingCodecState state,
}
- c->bufsize++;
sgi_finish_decode: ;
@@ -217,5 +279,5 @@ sgi_finish_decode: ;
state->errcode=err;
return -1;
}
- return state->count - c->bufsize;
+ return 0;
}
--
2.30.2
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