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gpt: harden set_gpt_info() against non NULL-terminated strings

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Strings read from devices may sometimes fail to be
NULL-terminated.   The functions in lib/string.c are subject to
failure in this case.   Protect against observed failures in
set_gpt_info() by switching to length-checking variants with a length
limit of the maximum possible partition table length.  At the same
time, add a few checks for NULL string pointers.

Here is an example as observed in sandbox under GDB:

    => gpt verify host 0 $partitions
    Program received signal SIGSEGV, Segmentation fault.
    0x0000000000477747 in strlen (s=0x0) at lib/string.c:267
    267             for (sc = s; *sc != '\0'; ++sc)
    (gdb) bt
    #0  0x0000000000477747 in strlen (s=0x0) at lib/string.c:267
    #1  0x00000000004140b2 in set_gpt_info (str_part=<optimized out>,
    str_disk_guid=str_disk_guid@entry=0x7fffffffdbe8, partitions=partitions@entry=0x7fffffffdbd8,
    parts_count=parts_count@entry=0x7fffffffdbcf "", dev_desc=<optimized out>) at cmd/gpt.c:415
    #2  0x00000000004145b9 in gpt_verify (str_part=<optimized out>, blk_dev_desc=0x7fffef09a9d0) at cmd/gpt.c:580
    #3  do_gpt (cmdtp=<optimized out>, flag=<optimized out>, argc=<optimized out>, argv=0x7fffef09a8f0)
    at cmd/gpt.c:783
    #4  0x00000000004295b0 in cmd_call (argv=0x7fffef09a8f0, argc=0x5, flag=<optimized out>,
    cmdtp=0x714e20 <_u_boot_list_2_cmd_2_gpt>) at common/command.c:500
    #5  cmd_process (flag=<optimized out>, argc=0x5, argv=0x7fffef09a8f0,
    repeatable=repeatable@entry=0x726c04 <flag_repeat>, ticks=ticks@entry=0x0) at common/command.c:539

Suggested-by: Lothar Waßmann <LW@karo-electronics.de>
Signed-off-by: Alison Chaiken <alison@peloton-tech.com>
This commit is contained in:
Alison Chaiken 2017-07-04 11:19:46 -07:00 committed by Tom Rini
parent 203f9b48ad
commit 2fcaa413b3
1 changed files with 36 additions and 27 deletions
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63
cmd/gpt.c
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@ -156,6 +156,25 @@ static bool found_key(const char *str, const char *key)
return result;
}
static int calc_parts_list_len(int numparts)
{
int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk=");
/* for the comma */
partlistlen++;
/* per-partition additions; numparts starts at 1, so this should be correct */
partlistlen += numparts * (strlen("name=,") + PART_NAME_LEN + 1);
/* see part.h for definition of struct disk_partition */
partlistlen += numparts * (strlen("start=MiB,") + sizeof(lbaint_t) + 1);
partlistlen += numparts * (strlen("size=MiB,") + sizeof(lbaint_t) + 1);
partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN + 1);
/* for the terminating null */
partlistlen++;
debug("Length of partitions_list is %d for %d partitions\n", partlistlen,
numparts);
return partlistlen;
}
#ifdef CONFIG_CMD_GPT_RENAME
static void del_gpt_info(void)
{
@ -234,25 +253,6 @@ static void print_gpt_info(void)
}
}
static int calc_parts_list_len(int numparts)
{
int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk=");
/* for the comma */
partlistlen++;
/* per-partition additions; numparts starts at 1, so this should be correct */
partlistlen += numparts * (strlen("name=,") + PART_NAME_LEN + 1);
/* see part.h for definition of struct disk_partition */
partlistlen += numparts * (strlen("start=MiB,") + sizeof(lbaint_t) + 1);
partlistlen += numparts * (strlen("size=MiB,") + sizeof(lbaint_t) + 1);
partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN + 1);
/* for the terminating null */
partlistlen++;
debug("Length of partitions_list is %d for %d partitions\n", partlistlen,
numparts);
return partlistlen;
}
/*
* create the string that upstream 'gpt write' command will accept as an
* argument
@ -385,6 +385,7 @@ static int set_gpt_info(struct blk_desc *dev_desc,
int errno = 0;
uint64_t size_ll, start_ll;
lbaint_t offset = 0;
int max_str_part = calc_parts_list_len(MAX_SEARCH_PARTITIONS);
debug("%s: lba num: 0x%x %d\n", __func__,
(unsigned int)dev_desc->lba, (unsigned int)dev_desc->lba);
@ -402,6 +403,8 @@ static int set_gpt_info(struct blk_desc *dev_desc,
if (!val) {
#ifdef CONFIG_RANDOM_UUID
*str_disk_guid = malloc(UUID_STR_LEN + 1);
if (str_disk_guid == NULL)
return -ENOMEM;
gen_rand_uuid_str(*str_disk_guid, UUID_STR_FORMAT_STD);
#else
free(str);
@ -416,10 +419,14 @@ static int set_gpt_info(struct blk_desc *dev_desc,
/* Move s to first partition */
strsep(&s, ";");
}
if (strlen(s) == 0)
if (s == NULL) {
printf("Error: is the partitions string NULL-terminated?\n");
return -EINVAL;
}
if (strnlen(s, max_str_part) == 0)
return -3;
i = strlen(s) - 1;
i = strnlen(s, max_str_part) - 1;
if (s[i] == ';')
s[i] = '\0';
@ -433,6 +440,8 @@ static int set_gpt_info(struct blk_desc *dev_desc,
/* allocate memory for partitions */
parts = calloc(sizeof(disk_partition_t), p_count);
if (parts == NULL)
return -ENOMEM;
/* retrieve partitions data from string */
for (i = 0; i < p_count; i++) {
@ -454,12 +463,12 @@ static int set_gpt_info(struct blk_desc *dev_desc,
} else {
if (extract_env(val, &p))
p = val;
if (strlen(p) >= sizeof(parts[i].uuid)) {
if (strnlen(p, max_str_part) >= sizeof(parts[i].uuid)) {
printf("Wrong uuid format for partition %d\n", i);
errno = -4;
goto err;
}
strcpy((char *)parts[i].uuid, p);
strncpy((char *)parts[i].uuid, p, max_str_part);
free(val);
}
#ifdef CONFIG_PARTITION_TYPE_GUID
@ -469,13 +478,13 @@ static int set_gpt_info(struct blk_desc *dev_desc,
/* 'type' is optional */
if (extract_env(val, &p))
p = val;
if (strlen(p) >= sizeof(parts[i].type_guid)) {
if (strnlen(p, max_str_part) >= sizeof(parts[i].type_guid)) {
printf("Wrong type guid format for partition %d\n",
i);
errno = -4;
goto err;
}
strcpy((char *)parts[i].type_guid, p);
strncpy((char *)parts[i].type_guid, p, max_str_part);
free(val);
}
#endif
@ -487,11 +496,11 @@ static int set_gpt_info(struct blk_desc *dev_desc,
}
if (extract_env(val, &p))
p = val;
if (strlen(p) >= sizeof(parts[i].name)) {
if (strnlen(p, max_str_part) >= sizeof(parts[i].name)) {
errno = -4;
goto err;
}
strcpy((char *)parts[i].name, p);
strncpy((char *)parts[i].name, p, max_str_part);
free(val);
/* size */