120 lines
4.7 KiB
Diff
120 lines
4.7 KiB
Diff
From eac15e252010c1189a5c0f461364dbe2cd2a68b1 Mon Sep 17 00:00:00 2001
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From: "Dustin L. Howett" <dustin@howett.net>
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Date: Thu, 9 May 2024 18:59:17 -0500
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Subject: [PATCH] rar4 reader: protect copy_from_lzss_window_to_unp() (#2172)
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copy_from_lzss_window_to_unp unnecessarily took an `int` parameter where
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both of its callers were holding a `size_t`.
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A lzss opcode chain could be constructed that resulted in a negative
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copy length, which when passed into memcpy would result in a very, very
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large positive number.
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Switching copy_from_lzss_window_to_unp to take a `size_t` allows it to
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properly bounds-check length.
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In addition, this patch also ensures that `length` is not itself larger
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than the destination buffer.
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Security: CVE-2024-20696
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---
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libarchive/archive_read_support_format_rar.c | 28 +++++++++++++-------
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1 file changed, 18 insertions(+), 10 deletions(-)
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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 4fc6626c..5776df4b 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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@@ -432,7 +432,7 @@ static int make_table_recurse(struct archive_read *, struct huffman_code *, int,
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struct huffman_table_entry *, int, int);
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static int expand(struct archive_read *, int64_t *);
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static int copy_from_lzss_window_to_unp(struct archive_read *, const void **,
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- int64_t, int);
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+ int64_t, size_t);
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static const void *rar_read_ahead(struct archive_read *, size_t, ssize_t *);
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static int parse_filter(struct archive_read *, const uint8_t *, uint16_t,
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uint8_t);
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@@ -2060,7 +2060,7 @@ read_data_compressed(struct archive_read *a, const void **buff, size_t *size,
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bs = rar->unp_buffer_size - rar->unp_offset;
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else
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bs = (size_t)rar->bytes_uncopied;
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- ret = copy_from_lzss_window_to_unp(a, buff, rar->offset, (int)bs);
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+ ret = copy_from_lzss_window_to_unp(a, buff, rar->offset, bs);
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if (ret != ARCHIVE_OK)
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return (ret);
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rar->offset += bs;
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@@ -2213,7 +2213,7 @@ read_data_compressed(struct archive_read *a, const void **buff, size_t *size,
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bs = rar->unp_buffer_size - rar->unp_offset;
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else
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bs = (size_t)rar->bytes_uncopied;
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- ret = copy_from_lzss_window_to_unp(a, buff, rar->offset, (int)bs);
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+ ret = copy_from_lzss_window_to_unp(a, buff, rar->offset, bs);
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if (ret != ARCHIVE_OK)
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return (ret);
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rar->offset += bs;
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@@ -3094,11 +3094,16 @@ copy_from_lzss_window(struct archive_read *a, void *buffer,
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static int
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copy_from_lzss_window_to_unp(struct archive_read *a, const void **buffer,
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- int64_t startpos, int length)
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+ int64_t startpos, size_t length)
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{
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int windowoffs, firstpart;
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struct rar *rar = (struct rar *)(a->format->data);
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+ if (length > rar->unp_buffer_size)
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+ {
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+ goto fatal;
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+ }
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+
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if (!rar->unp_buffer)
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{
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if ((rar->unp_buffer = malloc(rar->unp_buffer_size)) == NULL)
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@@ -3110,17 +3115,17 @@ copy_from_lzss_window_to_unp(struct archive_read *a, const void **buffer,
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}
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windowoffs = lzss_offset_for_position(&rar->lzss, startpos);
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- if(windowoffs + length <= lzss_size(&rar->lzss)) {
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+ if(windowoffs + length <= (size_t)lzss_size(&rar->lzss)) {
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memcpy(&rar->unp_buffer[rar->unp_offset], &rar->lzss.window[windowoffs],
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length);
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- } else if (length <= lzss_size(&rar->lzss)) {
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+ } else if (length <= (size_t)lzss_size(&rar->lzss)) {
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firstpart = lzss_size(&rar->lzss) - windowoffs;
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if (firstpart < 0) {
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archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
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"Bad RAR file data");
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return (ARCHIVE_FATAL);
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}
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- if (firstpart < length) {
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+ if ((size_t)firstpart < length) {
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memcpy(&rar->unp_buffer[rar->unp_offset],
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&rar->lzss.window[windowoffs], firstpart);
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memcpy(&rar->unp_buffer[rar->unp_offset + firstpart],
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@@ -3130,9 +3135,7 @@ copy_from_lzss_window_to_unp(struct archive_read *a, const void **buffer,
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&rar->lzss.window[windowoffs], length);
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}
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} else {
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- archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
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- "Bad RAR file data");
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- return (ARCHIVE_FATAL);
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+ goto fatal;
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}
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rar->unp_offset += length;
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if (rar->unp_offset >= rar->unp_buffer_size)
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@@ -3140,6 +3143,11 @@ copy_from_lzss_window_to_unp(struct archive_read *a, const void **buffer,
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else
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*buffer = NULL;
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return (ARCHIVE_OK);
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+
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+fatal:
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+ archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
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+ "Bad RAR file data");
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+ return (ARCHIVE_FATAL);
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}
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static const void *
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--
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2.45.1
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