--- /dev/null
+From 22b1db9d46654afc6f0c28f90af8cdc84a199f41 Mon Sep 17 00:00:00 2001
+From: Martin Matuska <martin@matuska.org>
+Date: Thu, 21 Nov 2019 03:08:40 +0100
+Subject: [PATCH] Bugfix and optimize archive_wstring_append_from_mbs()
+
+The cal to mbrtowc() or mbtowc() should read up to mbs_length
+bytes and not wcs_length. This avoids out-of-bounds reads.
+
+mbrtowc() and mbtowc() return (size_t)-1 wit errno EILSEQ when
+they encounter an invalid multibyte character and (size_t)-2 when
+they they encounter an incomplete multibyte character. As we return
+failure and all our callers error out it makes no sense to continue
+parsing mbs.
+
+As we allocate `len` wchars at the beginning and each wchar has
+at least one byte, there will never be need to grow the buffer,
+so the code can be left out. On the other hand, we are always
+allocatng more memory than we need.
+
+As long as wcs_length == mbs_length == len we can omit wcs_length.
+We keep the old code commented if we decide to save memory and
+use autoexpanding wcs_length in the future.
+
+Fixes #1276
+
+Upstream-Status: Backport [https://github.com/libarchive/libarchive/commit/22b1db9d46654afc6f0c28f90af8cdc84a199f41]
+CVE: CVE-2019-19221
+Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
+---
+ libarchive/archive_string.c | 28 +++++++++++++++++-----------
+ 1 file changed, 17 insertions(+), 11 deletions(-)
+
+diff --git a/libarchive/archive_string.c b/libarchive/archive_string.c
+index 979a418b6..bd39c96f1 100644
+--- a/libarchive/archive_string.c
++++ b/libarchive/archive_string.c
+@@ -591,7 +591,7 @@ archive_wstring_append_from_mbs(struct archive_wstring *dest,
+ * No single byte will be more than one wide character,
+ * so this length estimate will always be big enough.
+ */
+- size_t wcs_length = len;
++ // size_t wcs_length = len;
+ size_t mbs_length = len;
+ const char *mbs = p;
+ wchar_t *wcs;
+@@ -600,7 +600,11 @@ archive_wstring_append_from_mbs(struct archive_wstring *dest,
+
+ memset(&shift_state, 0, sizeof(shift_state));
+ #endif
+- if (NULL == archive_wstring_ensure(dest, dest->length + wcs_length + 1))
++ /*
++ * As we decided to have wcs_length == mbs_length == len
++ * we can use len here instead of wcs_length
++ */
++ if (NULL == archive_wstring_ensure(dest, dest->length + len + 1))
+ return (-1);
+ wcs = dest->s + dest->length;
+ /*
+@@ -609,6 +613,12 @@ archive_wstring_append_from_mbs(struct archive_wstring *dest,
+ * multi bytes.
+ */
+ while (*mbs && mbs_length > 0) {
++ /*
++ * The buffer we allocated is always big enough.
++ * Keep this code path in a comment if we decide to choose
++ * smaller wcs_length in the future
++ */
++/*
+ if (wcs_length == 0) {
+ dest->length = wcs - dest->s;
+ dest->s[dest->length] = L'\0';
+@@ -618,24 +628,20 @@ archive_wstring_append_from_mbs(struct archive_wstring *dest,
+ return (-1);
+ wcs = dest->s + dest->length;
+ }
++*/
+ #if HAVE_MBRTOWC
+- r = mbrtowc(wcs, mbs, wcs_length, &shift_state);
++ r = mbrtowc(wcs, mbs, mbs_length, &shift_state);
+ #else
+- r = mbtowc(wcs, mbs, wcs_length);
++ r = mbtowc(wcs, mbs, mbs_length);
+ #endif
+ if (r == (size_t)-1 || r == (size_t)-2) {
+ ret_val = -1;
+- if (errno == EILSEQ) {
+- ++mbs;
+- --mbs_length;
+- continue;
+- } else
+- break;
++ break;
+ }
+ if (r == 0 || r > mbs_length)
+ break;
+ wcs++;
+- wcs_length--;
++ // wcs_length--;
+ mbs += r;
+ mbs_length -= r;
+ }
