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