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