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base64: fix possible null pointer dereference

clang-10 analyzer reports following:

 base64.c:325:20: warning: Array access (from variable 'target') results in a null pointer dereference
                 target[tarindex] = 0;
                 ~~~~~~           ^

and prepared test case confirms it:

 Invalid write of size 1
    at 0x4E4463F: b64_decode (base64.c:325)
    by 0x40088C: test_invalid_inputs (tests/test-base64.c:26)
    by 0x40088C: main (tests/test-base64.c:32)
  Address 0x1 is not stack'd, malloc'd or (recently) free'd

 Process terminating with default action of signal 11 (SIGSEGV)
  Access not within mapped region at address 0x1
    at 0x4E4463F: b64_decode (base64.c:325)
    by 0x40088C: test_invalid_inputs (tests/test-base64.c:26)
    by 0x40088C: main (tests/test-base64.c:32)

Signed-off-by: Petr Štetiar <ynezz@true.cz>
master
Petr Štetiar 1 year ago
parent
commit
0003ea9c45
4 changed files with 32 additions and 0 deletions
  1. +6
    -0
      base64.c
  2. +12
    -0
      tests/cram/test_base64.t
  3. +7
    -0
      tests/test-b64_decode.c
  4. +7
    -0
      tests/test-b64_encode.c

+ 6
- 0
base64.c View File

@ -65,6 +65,8 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "assert.h"
#include "utils.h"
static const char Base64[] =
@ -144,6 +146,8 @@ int b64_encode(const void *_src, size_t srclength,
u_char output[4];
size_t i;
assert(dest && targsize > 0);
while (2 < srclength) {
input[0] = *src++;
input[1] = *src++;
@ -208,6 +212,8 @@ int b64_decode(const void *_src, void *dest, size_t targsize)
state = 0;
tarindex = 0;
assert(dest && targsize > 0);
while ((ch = (unsigned char)*src++) != '\0') {
if (isspace(ch)) /* Skip whitespace anywhere. */
continue;

+ 12
- 0
tests/cram/test_base64.t View File

@ -19,3 +19,15 @@ check that base64 is producing expected results:
4 foob
5 fooba
6 foobar
check that b64_encode and b64_decode assert invalid input
$ alias check="egrep '(dumped|Assertion)' | sed 's;.*\(b64_.*code\).*\(Assertion.*$\);\1: \2;' | LC_ALL=C sort"
$ test-b64_decode 2>&1 | check
Aborted (core dumped)
b64_decode: Assertion `dest && targsize > 0' failed.
$ test-b64_encode 2>&1 | check
Aborted (core dumped)
b64_encode: Assertion `dest && targsize > 0' failed.

+ 7
- 0
tests/test-b64_decode.c View File

@ -0,0 +1,7 @@
#include "utils.h"
int main()
{
b64_decode("Zg==", NULL, 2);
return 0;
}

+ 7
- 0
tests/test-b64_encode.c View File

@ -0,0 +1,7 @@
#include "utils.h"
int main()
{
b64_encode("foo", 3, NULL, 2);
return 0;
}

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