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From 97f964e3e0ce3ae34bfb4c366a37ba7c0d9610a6 Mon Sep 17 00:00:00 2001 |
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From: Tim Kientzle <kientzle@acm.org> |
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Date: Sat, 7 Feb 2015 12:35:33 -0800 |
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Subject: [PATCH] Issue 403: Buffer underflow parsing 'ar' header |
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|
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While pruning trailing text from ar filenames, we did not |
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check for an empty filename. This results in reading the byte |
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before the filename on the stack. |
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|
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While here, change a number of ar format issues from WARN to FATAL. |
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It's better to abort on a damaged file than risk reading garbage. |
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No doubt, this will require additional tuning in the future. |
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--- |
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libarchive/archive_read_support_format_ar.c | 21 ++++++++++++++------- |
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1 file changed, 14 insertions(+), 7 deletions(-) |
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|
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diff --git a/libarchive/archive_read_support_format_ar.c b/libarchive/archive_read_support_format_ar.c |
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index 82756c9..4b5b66b 100644 |
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--- a/libarchive/archive_read_support_format_ar.c |
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+++ b/libarchive/archive_read_support_format_ar.c |
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@@ -180,7 +180,7 @@ _ar_read_header(struct archive_read *a, struct archive_entry *entry, |
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if (strncmp(h + AR_fmag_offset, "`\n", 2) != 0) { |
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archive_set_error(&a->archive, EINVAL, |
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"Incorrect file header signature"); |
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- return (ARCHIVE_WARN); |
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+ return (ARCHIVE_FATAL); |
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} |
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|
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/* Copy filename into work buffer. */ |
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@@ -239,8 +239,15 @@ _ar_read_header(struct archive_read *a, struct archive_entry *entry, |
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* and are not terminated in '/', so we don't trim anything |
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* that starts with '/'.) |
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*/ |
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- if (filename[0] != '/' && *p == '/') |
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+ if (filename[0] != '/' && p > filename && *p == '/') { |
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*p = '\0'; |
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+ } |
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+ |
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+ if (p < filename) { |
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+ archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC, |
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+ "Found entry with empty filename"); |
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+ return (ARCHIVE_FATAL); |
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+ } |
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|
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/* |
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* '//' is the GNU filename table. |
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@@ -262,12 +269,12 @@ _ar_read_header(struct archive_read *a, struct archive_entry *entry, |
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if (entry_size == 0) { |
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archive_set_error(&a->archive, EINVAL, |
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"Invalid string table"); |
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- return (ARCHIVE_WARN); |
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+ return (ARCHIVE_FATAL); |
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} |
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if (ar->strtab != NULL) { |
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archive_set_error(&a->archive, EINVAL, |
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"More than one string tables exist"); |
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- return (ARCHIVE_WARN); |
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+ return (ARCHIVE_FATAL); |
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} |
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|
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/* Read the filename table into memory. */ |
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@@ -311,11 +318,11 @@ _ar_read_header(struct archive_read *a, struct archive_entry *entry, |
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*/ |
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if (ar->strtab == NULL || number > ar->strtab_size) { |
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archive_set_error(&a->archive, EINVAL, |
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- "Can't find long filename for entry"); |
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+ "Can't find long filename for GNU/SVR4 archive entry"); |
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archive_entry_copy_pathname(entry, filename); |
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/* Parse the time, owner, mode, size fields. */ |
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ar_parse_common_header(ar, entry, h); |
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- return (ARCHIVE_WARN); |
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+ return (ARCHIVE_FATAL); |
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} |
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|
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archive_entry_copy_pathname(entry, &ar->strtab[(size_t)number]); |
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@@ -573,7 +580,7 @@ bad_string_table: |
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"Invalid string table"); |
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free(ar->strtab); |
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ar->strtab = NULL; |
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- return (ARCHIVE_WARN); |
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+ return (ARCHIVE_FATAL); |
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} |
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|
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static uint64_t |
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-- |
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2.7.4 |
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