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unzip: fix a case where we find wrong CDE. Closes 8821

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function                                             old     new   delta
unzip_main                                          2472    2490     +18

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-04-17 21:05:34 +02:00
parent 84ba50c32f
commit 0ccf52a9fb
1 changed files with 35 additions and 8 deletions
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41
archival/unzip.c
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@ -45,6 +45,12 @@
#include "libbb.h"
#include "bb_archive.h"
#if 0
# define dbg(...) bb_error_msg(__VA_ARGS__)
#else
# define dbg(...) ((void)0)
#endif
enum {
#if BB_BIG_ENDIAN
ZIP_FILEHEADER_MAGIC = 0x504b0304,
@ -193,15 +199,17 @@ static uint32_t find_cdf_offset(void)
unsigned char *p;
off_t end;
unsigned char *buf = xzalloc(PEEK_FROM_END);
uint32_t found;
end = xlseek(zip_fd, 0, SEEK_END);
end -= PEEK_FROM_END;
if (end < 0)
end = 0;
dbg("Looking for cdf_offset starting from 0x%"OFF_FMT"x", end);
xlseek(zip_fd, end, SEEK_SET);
full_read(zip_fd, buf, PEEK_FROM_END);
cde_header.formatted.cdf_offset = BAD_CDF_OFFSET;
found = BAD_CDF_OFFSET;
p = buf;
while (p <= buf + PEEK_FROM_END - CDE_HEADER_LEN - 4) {
if (*p != 'P') {
@ -220,14 +228,25 @@ static uint32_t find_cdf_offset(void)
/*
* I've seen .ZIP files with seemingly valid CDEs
* where cdf_offset points past EOF - ??
* Ignore such CDEs:
* This check ignores such CDEs:
*/
if (cde_header.formatted.cdf_offset < end + (p - buf))
break;
cde_header.formatted.cdf_offset = BAD_CDF_OFFSET;
if (cde_header.formatted.cdf_offset < end + (p - buf)) {
found = cde_header.formatted.cdf_offset;
dbg("Possible cdf_offset:0x%x at 0x%"OFF_FMT"x",
(unsigned)found, end + (p-3 - buf));
dbg(" cdf_offset+cdf_size:0x%x",
(unsigned)(found + SWAP_LE32(cde_header.formatted.cdf_size)));
/*
* We do not "break" here because only the last CDE is valid.
* I've seen a .zip archive which contained a .zip file,
* uncompressed, and taking the first CDE was using
* the CDE inside that file!
*/
}
}
free(buf);
return cde_header.formatted.cdf_offset;
dbg("Found cdf_offset:0x%x", (unsigned)found);
return found;
};
static uint32_t read_next_cdf(uint32_t cdf_offset, cdf_header_t *cdf_ptr)
@ -240,9 +259,13 @@ static uint32_t read_next_cdf(uint32_t cdf_offset, cdf_header_t *cdf_ptr)
cdf_offset = find_cdf_offset();
if (cdf_offset != BAD_CDF_OFFSET) {
dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
xlseek(zip_fd, cdf_offset + 4, SEEK_SET);
xread(zip_fd, cdf_ptr->raw, CDF_HEADER_LEN);
FIX_ENDIANNESS_CDF(*cdf_ptr);
dbg("file_name_length:%u", (unsigned)cdf_ptr->formatted.file_name_length);
dbg("extra_field_length:%u", (unsigned)cdf_ptr->formatted.extra_field_length);
dbg("file_comment_length:%u", (unsigned)cdf_ptr->formatted.file_comment_length);
cdf_offset += 4 + CDF_HEADER_LEN
+ cdf_ptr->formatted.file_name_length
+ cdf_ptr->formatted.extra_field_length
@ -532,11 +555,14 @@ int unzip_main(int argc, char **argv)
/* Check magic number */
xread(zip_fd, &magic, 4);
/* Central directory? It's at the end, so exit */
if (magic == ZIP_CDF_MAGIC)
if (magic == ZIP_CDF_MAGIC) {
dbg("got ZIP_CDF_MAGIC");
break;
}
#if ENABLE_DESKTOP
/* Data descriptor? It was a streaming file, go on */
if (magic == ZIP_DD_MAGIC) {
dbg("got ZIP_DD_MAGIC");
/* skip over duplicate crc32, cmpsize and ucmpsize */
unzip_skip(3 * 4);
continue;
@ -544,6 +570,7 @@ int unzip_main(int argc, char **argv)
#endif
if (magic != ZIP_FILEHEADER_MAGIC)
bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
dbg("got ZIP_FILEHEADER_MAGIC");
/* Read the file header */
xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);