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@@ -0,0 +1,81 @@
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+From bfcfe6f04ed20db2504db8a254d1f40a1d84eb28 Mon Sep 17 00:00:00 2001
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+From: Daniel Axtens <dja@axtens.net>
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+Date: Tue, 4 Dec 2018 00:55:22 +1100
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+Subject: [PATCH] rar: file split across multi-part archives must match
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+
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+Fuzzing uncovered some UAF and memory overrun bugs where a file in a
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+single file archive reported that it was split across multiple
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+volumes. This was caused by ppmd7 operations calling
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+rar_br_fillup. This would invoke rar_read_ahead, which would in some
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+situations invoke archive_read_format_rar_read_header. That would
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+check the new file name against the old file name, and if they didn't
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+match up it would free the ppmd7 buffer and allocate a new
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+one. However, because the ppmd7 decoder wasn't actually done with the
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+buffer, it would continue to used the freed buffer. Both reads and
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+writes to the freed region can be observed.
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+
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+This is quite tricky to solve: once the buffer has been freed it is
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+too late, as the ppmd7 decoder functions almost universally assume
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+success - there's no way for ppmd_read to signal error, nor are there
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+good ways for functions like Range_Normalise to propagate them. So we
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+can't detect after the fact that we're in an invalid state - e.g. by
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+checking rar->cursor, we have to prevent ourselves from ever ending up
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+there. So, when we are in the dangerous part or rar_read_ahead that
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+assumes a valid split, we set a flag force read_header to either go
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+down the path for split files or bail. This means that the ppmd7
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+decoder keeps a valid buffer and just runs out of data.
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+
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+Found with a combination of AFL, afl-rb and qsym.
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+---
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+ libarchive/archive_read_support_format_rar.c | 9 +++++++++
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+ 1 file changed, 9 insertions(+)
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+
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+[for import into Buildroot]
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+Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
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+Upstream-status: backport
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+
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+CVE-2018-1000878
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+
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+diff --git a/libarchive/archive_read_support_format_rar.c b/libarchive/archive_read_support_format_rar.c
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+index 6f419c27..a8cc5c94 100644
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+--- a/libarchive/archive_read_support_format_rar.c
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++++ b/libarchive/archive_read_support_format_rar.c
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+@@ -258,6 +258,7 @@ struct rar
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+ struct data_block_offsets *dbo;
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+ unsigned int cursor;
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+ unsigned int nodes;
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++ char filename_must_match;
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+
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+ /* LZSS members */
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+ struct huffman_code maincode;
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+@@ -1560,6 +1561,12 @@ read_header(struct archive_read *a, struct archive_entry *entry,
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+ }
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+ return ret;
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+ }
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++ else if (rar->filename_must_match)
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++ {
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++ archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
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++ "Mismatch of file parts split across multi-volume archive");
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++ return (ARCHIVE_FATAL);
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++ }
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+
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+ rar->filename_save = (char*)realloc(rar->filename_save,
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+ filename_size + 1);
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+@@ -2933,12 +2940,14 @@ rar_read_ahead(struct archive_read *a, size_t min, ssize_t *avail)
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+ else if (*avail == 0 && rar->main_flags & MHD_VOLUME &&
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+ rar->file_flags & FHD_SPLIT_AFTER)
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+ {
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++ rar->filename_must_match = 1;
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+ ret = archive_read_format_rar_read_header(a, a->entry);
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+ if (ret == (ARCHIVE_EOF))
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+ {
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+ rar->has_endarc_header = 1;
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+ ret = archive_read_format_rar_read_header(a, a->entry);
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+ }
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++ rar->filename_must_match = 0;
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+ if (ret != (ARCHIVE_OK))
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+ return NULL;
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+ return rar_read_ahead(a, min, avail);
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+--
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+2.19.2
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+
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Thomas De Schampheleire