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authorPeter Korsgaard <jacmet@sunsite.dk>2013-09-10 09:52:35 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-09-10 14:22:12 (GMT)
commit2a053a2430e8de2f5de3da7d4d25343f61161f09 (patch)
treeecf4d1bc83b7f7ec3672758d81f3eec5a346246f
parentdc57294485068e644714804ad1b1a3a10c4fceec (diff)
downloadbusybox-2a053a2430e8de2f5de3da7d4d25343f61161f09.tar.gz
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ar: read_num(): fix reading fields using the entire width
ar fields are fixed length text strings (padded with spaces). Ensure bb_strtou doesn't read past the field in case the full width is used. The fields are only read once, so the simplest/smallest solution to me seems to be to just pass the length to read_num() and then zero terminate the string before passing it to bb_strtou. This does mean that the fields MUST be read in reverse order, so some minor reshuffling was needed. Bloat-o-meter: function old new delta get_header_ar 394 414 +20 read_num 29 36 +7 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 27/0) Total: 27 bytes Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--archival/libarchive/get_header_ar.c32
1 files changed, 20 insertions, 12 deletions
diff --git a/archival/libarchive/get_header_ar.c b/archival/libarchive/get_header_ar.c
index 23c4124..f655585 100644
--- a/archival/libarchive/get_header_ar.c
+++ b/archival/libarchive/get_header_ar.c
@@ -8,11 +8,19 @@
#include "bb_archive.h"
#include "ar.h"
-static unsigned read_num(const char *str, int base)
+/* WARNING: Clobbers str[len], so fields must be read in reverse order! */
+static unsigned read_num(char *str, int base, int len)
{
+ int err;
+
+ /* ar fields are fixed length text strings (padded with spaces).
+ * Ensure bb_strtou doesn't read past the field in case the full
+ * width is used. */
+ str[len] = 0;
+
/* This code works because
* on misformatted numbers bb_strtou returns all-ones */
- int err = bb_strtou(str, NULL, base);
+ err = bb_strtou(str, NULL, base);
if (err == -1)
bb_error_msg_and_die("invalid ar header");
return err;
@@ -51,11 +59,8 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
if (ar.formatted.magic[0] != '`' || ar.formatted.magic[1] != '\n')
bb_error_msg_and_die("invalid ar header");
- /* FIXME: more thorough routine would be in order here
- * (we have something like that in tar)
- * but for now we are lax. */
- ar.formatted.magic[0] = '\0'; /* else 4G-2 file will have size="4294967294`\n..." */
- typed->size = size = read_num(ar.formatted.size, 10);
+ typed->size = size = read_num(ar.formatted.size, 10,
+ sizeof(ar.formatted.size));
/* special filenames have '/' as the first character */
if (ar.formatted.name[0] == '/') {
@@ -86,11 +91,13 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
/* Only size is always present, the rest may be missing in
* long filename pseudo file. Thus we decode the rest
* after dealing with long filename pseudo file.
+ * Note that the fields MUST be read in reverse order as
+ * read_num() clobbers the next byte after the field!
*/
- typed->mode = read_num(ar.formatted.mode, 8);
- typed->mtime = read_num(ar.formatted.date, 10);
- typed->uid = read_num(ar.formatted.uid, 10);
- typed->gid = read_num(ar.formatted.gid, 10);
+ typed->mode = read_num(ar.formatted.mode, 8, sizeof(ar.formatted.mode));
+ typed->gid = read_num(ar.formatted.gid, 10, sizeof(ar.formatted.gid));
+ typed->uid = read_num(ar.formatted.uid, 10, sizeof(ar.formatted.uid));
+ typed->mtime = read_num(ar.formatted.date, 10, sizeof(ar.formatted.date));
#if ENABLE_FEATURE_AR_LONG_FILENAMES
if (ar.formatted.name[0] == '/') {
@@ -98,7 +105,8 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
/* The number after the '/' indicates the offset in the ar data section
* (saved in ar_long_names) that conatains the real filename */
- long_offset = read_num(&ar.formatted.name[1], 10);
+ long_offset = read_num(&ar.formatted.name[1], 10,
+ sizeof(ar.formatted.name) - 1);
if (long_offset >= ar_long_name_size) {
bb_error_msg_and_die("can't resolve long filename");
}