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From 021efa522ad729ff0f5806c4ce53e4a6cc1daa31 Mon Sep 17 00:00:00 2001
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From: Daniel Axtens <dja@axtens.net>
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Date: Tue, 20 Nov 2018 17:56:29 +1100
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Subject: [PATCH] Avoid a double-free when a window size of 0 is specified
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new_size can be 0 with a malicious or corrupted RAR archive.
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realloc(area, 0) is equivalent to free(area), so the region would
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be free()d here and the free()d again in the cleanup function.
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Found with a setup running AFL, afl-rb, and qsym.
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---
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libarchive/archive_read_support_format_rar.c | 5 +++++
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1 file changed, 5 insertions(+)
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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 234522229..6f419c270 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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@@ -2300,6 +2300,11 @@ parse_codes(struct archive_read *a)
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new_size = DICTIONARY_MAX_SIZE;
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else
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new_size = rar_fls((unsigned int)rar->unp_size) << 1;
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+ if (new_size == 0) {
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+ archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
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+ "Zero window size is invalid.");
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+ return (ARCHIVE_FATAL);
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+ }
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new_window = realloc(rar->lzss.window, new_size);
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if (new_window == NULL) {
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archive_set_error(&a->archive, ENOMEM,
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