From: Alison Chaiken alison@peloton-tech.com
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 --- cmd/gpt.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/cmd/gpt.c b/cmd/gpt.c index 73bf273..8bd7bdf 100644 --- a/cmd/gpt.c +++ b/cmd/gpt.c @@ -233,7 +233,7 @@ static void print_gpt_info(void) } }
-#ifdef CONFIG_CMD_GPT_RENAME + static int calc_parts_list_len(int numparts) { int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk="); @@ -253,6 +253,7 @@ static int calc_parts_list_len(int numparts) return partlistlen; }
+#ifdef CONFIG_CMD_GPT_RENAME /* * create the string that upstream 'gpt write' command will accept as an * argument @@ -381,6 +382,7 @@ 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); @@ -398,6 +400,8 @@ 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); @@ -412,10 +416,14 @@ 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';
@@ -429,6 +437,8 @@ 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++) { @@ -450,12 +460,12 @@ 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 @@ -465,13 +475,13 @@ 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 @@ -483,11 +493,11 @@ 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 */