0038-CVE-2018-18557.patch
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From ac1ad5a48fe981a8a9b6911886894520bbe0c71e Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sun, 14 Oct 2018 16:38:29 +0200
Subject: [PATCH 09/10] JBIG: fix potential out-of-bounds write in JBIGDecode()
JBIGDecode doesn't check if the user provided buffer is large enough
to store the JBIG decoded image, which can potentially cause out-of-bounds
write in the buffer.
This issue was reported and analyzed by Thomas Dullien.
Also fixes a (harmless) potential use of uninitialized memory when
tif->tif_rawsize > tif->tif_rawcc
And in case libtiff is compiled with CHUNKY_STRIP_READ_SUPPORT, make sure
that whole strip data is provided to JBIGDecode()
---
libtiff/tif_jbig.c | 32 ++++++++++++++++++++++++++------
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/libtiff/tif_jbig.c b/libtiff/tif_jbig.c
index 37878f6..667f3ff 100644
--- a/libtiff/tif_jbig.c
+++ b/libtiff/tif_jbig.c
@@ -53,17 +53,18 @@ static int JBIGDecode(TIFF* tif, uint8* buffer, tmsize_t size, uint16 s)
struct jbg_dec_state decoder;
int decodeStatus = 0;
unsigned char* pImage = NULL;
- (void) size, (void) s;
+ unsigned long decodedSize;
+ (void) s;
if (isFillOrder(tif, tif->tif_dir.td_fillorder))
{
- TIFFReverseBits(tif->tif_rawdata, tif->tif_rawdatasize);
+ TIFFReverseBits(tif->tif_rawcp, tif->tif_rawcc);
}
jbg_dec_init(&decoder);
#if defined(HAVE_JBG_NEWLEN)
- jbg_newlen(tif->tif_rawdata, (size_t)tif->tif_rawdatasize);
+ jbg_newlen(tif->tif_rawcp, (size_t)tif->tif_rawcc);
/*
* I do not check the return status of jbg_newlen because even if this
* function fails it does not necessarily mean that decoding the image
@@ -76,8 +77,8 @@ static int JBIGDecode(TIFF* tif, uint8* buffer, tmsize_t size, uint16 s)
*/
#endif /* HAVE_JBG_NEWLEN */
- decodeStatus = jbg_dec_in(&decoder, (unsigned char*)tif->tif_rawdata,
- (size_t)tif->tif_rawdatasize, NULL);
+ decodeStatus = jbg_dec_in(&decoder, (unsigned char*)tif->tif_rawcp,
+ (size_t)tif->tif_rawcc, NULL);
if (JBG_EOK != decodeStatus)
{
/*
@@ -97,9 +98,28 @@ static int JBIGDecode(TIFF* tif, uint8* buffer, tmsize_t size, uint16 s)
return 0;
}
+ decodedSize = jbg_dec_getsize(&decoder);
+ if( (tmsize_t)decodedSize < size )
+ {
+ TIFFWarningExt(tif->tif_clientdata, "JBIG",
+ "Only decoded %lu bytes, whereas %lu requested",
+ decodedSize, (unsigned long)size);
+ }
+ else if( (tmsize_t)decodedSize > size )
+ {
+ TIFFErrorExt(tif->tif_clientdata, "JBIG",
+ "Decoded %lu bytes, whereas %lu were requested",
+ decodedSize, (unsigned long)size);
+ jbg_dec_free(&decoder);
+ return 0;
+ }
pImage = jbg_dec_getimage(&decoder, 0);
- _TIFFmemcpy(buffer, pImage, jbg_dec_getsize(&decoder));
+ _TIFFmemcpy(buffer, pImage, decodedSize);
jbg_dec_free(&decoder);
+
+ tif->tif_rawcp += tif->tif_rawcc;
+ tif->tif_rawcc = 0;
+
return 1;
}
--
2.17.2