From ca71eda33fe8421f98fbe20eb4392473357c1c43 Mon Sep 17 00:00:00 2001 From: Changqing Li Date: Wed, 30 Dec 2020 10:22:47 +0800 Subject: [PATCH] fixed another unsigned integer overflow first fixed by google in android fork, https://android.googlesource.com/platform/external/libexif/+/1e187b62682ffab5003c702657d6d725b4278f16%5E%21/#F0 (use a more generic overflow check method, also check second overflow instance.) https://security-tracker.debian.org/tracker/CVE-2020-0198 Upstream-Status: Backport[https://github.com/libexif/libexif/commit/ce03ad7ef4e8aeefce79192bf5b6f69fae396f0c] CVE: CVE-2020-0198 Signed-off-by: Changqing Li --- libexif/exif-data.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/libexif/exif-data.c b/libexif/exif-data.c index 8b280d3..34d58fc 100644 --- a/libexif/exif-data.c +++ b/libexif/exif-data.c @@ -47,6 +47,8 @@ #undef JPEG_MARKER_APP1 #define JPEG_MARKER_APP1 0xe1 +#define CHECKOVERFLOW(offset,datasize,structsize) (( offset >= datasize) || (structsize > datasize) || (offset > datasize - structsize )) + static const unsigned char ExifHeader[] = {0x45, 0x78, 0x69, 0x66, 0x00, 0x00}; struct _ExifDataPrivate @@ -327,7 +329,7 @@ exif_data_load_data_thumbnail (ExifData *data, const unsigned char *d, exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail offset (%u).", o); return; } - if (s > ds - o) { + if (CHECKOVERFLOW(o,ds,s)) { exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail size (%u), max would be %u.", s, ds-o); return; } @@ -420,9 +422,9 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd, } /* Read the number of entries */ - if ((offset + 2 < offset) || (offset + 2 < 2) || (offset + 2 > ds)) { + if (CHECKOVERFLOW(offset, ds, 2)) { exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData", - "Tag data past end of buffer (%u > %u)", offset+2, ds); + "Tag data past end of buffer (%u+2 > %u)", offset, ds); return; } n = exif_get_short (d + offset, data->priv->order); @@ -431,7 +433,7 @@ exif_data_load_data_content (ExifData *data, ExifIfd ifd, offset += 2; /* Check if we have enough data. */ - if (offset + 12 * n > ds) { + if (CHECKOVERFLOW(offset, ds, 12*n)) { n = (ds - offset) / 12; exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Short data; only loading %hu entries...", n); -- 2.17.1