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tftp: prevent overwriting reserved memory

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This fixes CVE-2018-18439 ("insufficient boundary checks in network
image boot") by using lmb to check for a valid range to store
received blocks.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
[trini: Always build lib/lmb.o on LMB and lib/fdtdec.o on OF_LIBFDT]
Signed-off-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Simon Goldschmidt 2019-01-14 22:38:22 +01:00 committed by Tom Rini
parent a85c213f47
commit a156c47e39
2 changed files with 64 additions and 11 deletions
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4
lib/Makefile
View File

@ -30,14 +30,12 @@ obj-y += crc7.o
obj-y += crc8.o
obj-y += crc16.o
obj-$(CONFIG_ERRNO_STR) += errno_str.o
obj-$(CONFIG_OF_LIBFDT) += fdtdec.o
obj-$(CONFIG_FIT) += fdtdec_common.o
obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o
obj-$(CONFIG_GZIP_COMPRESSED) += gzip.o
obj-$(CONFIG_GENERATE_SMBIOS_TABLE) += smbios.o
obj-$(CONFIG_IMAGE_SPARSE) += image-sparse.o
obj-y += initcall.o
obj-$(CONFIG_LMB) += lmb.o
obj-y += ldiv.o
obj-$(CONFIG_MD5) += md5.o
obj-y += net_utils.o
@ -89,9 +87,11 @@ obj-y += crc32.o
obj-$(CONFIG_CRC32C) += crc32c.o
obj-y += ctype.o
obj-y += div64.o
obj-$(CONFIG_OF_LIBFDT) += fdtdec.o
obj-y += hang.o
obj-y += linux_compat.o
obj-y += linux_string.o
obj-$(CONFIG_LMB) += lmb.o
obj-y += membuff.o
obj-$(CONFIG_REGEX) += slre.o
obj-y += string.o

71
net/tftp.c
View File

@ -17,6 +17,8 @@
#include <flash.h>
#endif
DECLARE_GLOBAL_DATA_PTR;
/* Well known TFTP port # */
#define WELL_KNOWN_PORT 69
/* Millisecs to timeout for lost pkt */
@ -81,6 +83,10 @@ static ulong tftp_block_wrap;
/* memory offset due to wrapping */
static ulong tftp_block_wrap_offset;
static int tftp_state;
static ulong tftp_load_addr;
#ifdef CONFIG_LMB
static ulong tftp_load_size;
#endif
#ifdef CONFIG_TFTP_TSIZE
/* The file size reported by the server */
static int tftp_tsize;
@ -164,10 +170,11 @@ static void mcast_cleanup(void)
#endif /* CONFIG_MCAST_TFTP */
static inline void store_block(int block, uchar *src, unsigned len)
static inline int store_block(int block, uchar *src, unsigned int len)
{
ulong offset = block * tftp_block_size + tftp_block_wrap_offset;
ulong newsize = offset + len;
ulong store_addr = tftp_load_addr + offset;
#ifdef CONFIG_SYS_DIRECT_FLASH_TFTP
int i, rc = 0;
@ -175,24 +182,32 @@ static inline void store_block(int block, uchar *src, unsigned len)
/* start address in flash? */
if (flash_info[i].flash_id == FLASH_UNKNOWN)
continue;
if (load_addr + offset >= flash_info[i].start[0]) {
if (store_addr >= flash_info[i].start[0]) {
rc = 1;
break;
}
}
if (rc) { /* Flash is destination for this packet */
rc = flash_write((char *)src, (ulong)(load_addr+offset), len);
rc = flash_write((char *)src, store_addr, len);
if (rc) {
flash_perror(rc);
net_set_state(NETLOOP_FAIL);
return;
return rc;
}
} else
#endif /* CONFIG_SYS_DIRECT_FLASH_TFTP */
{
void *ptr = map_sysmem(load_addr + offset, len);
void *ptr;
#ifdef CONFIG_LMB
if (store_addr < tftp_load_addr ||
store_addr + len > tftp_load_addr + tftp_load_size) {
puts("\nTFTP error: ");
puts("trying to overwrite reserved memory...\n");
return -1;
}
#endif
ptr = map_sysmem(store_addr, len);
memcpy(ptr, src, len);
unmap_sysmem(ptr);
}
@ -203,6 +218,8 @@ static inline void store_block(int block, uchar *src, unsigned len)
if (net_boot_file_size < newsize)
net_boot_file_size = newsize;
return 0;
}
/* Clear our state ready for a new transfer */
@ -606,7 +623,11 @@ static void tftp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
timeout_count_max = tftp_timeout_count_max;
net_set_timeout_handler(timeout_ms, tftp_timeout_handler);
store_block(tftp_cur_block - 1, pkt + 2, len);
if (store_block(tftp_cur_block - 1, pkt + 2, len)) {
eth_halt();
net_set_state(NETLOOP_FAIL);
break;
}
/*
* Acknowledge the block just received, which will prompt
@ -695,6 +716,25 @@ static void tftp_timeout_handler(void)
}
}
/* Initialize tftp_load_addr and tftp_load_size from load_addr and lmb */
static int tftp_init_load_addr(void)
{
#ifdef CONFIG_LMB
struct lmb lmb;
phys_size_t max_size;
lmb_init_and_reserve(&lmb, gd->bd->bi_dram[0].start,
gd->bd->bi_dram[0].size, (void *)gd->fdt_blob);
max_size = lmb_get_unreserved_size(&lmb, load_addr);
if (!max_size)
return -1;
tftp_load_size = max_size;
#endif
tftp_load_addr = load_addr;
return 0;
}
void tftp_start(enum proto_t protocol)
{
@ -791,7 +831,14 @@ void tftp_start(enum proto_t protocol)
} else
#endif
{
printf("Load address: 0x%lx\n", load_addr);
if (tftp_init_load_addr()) {
eth_halt();
net_set_state(NETLOOP_FAIL);
puts("\nTFTP error: ");
puts("trying to overwrite reserved memory...\n");
return;
}
printf("Load address: 0x%lx\n", tftp_load_addr);
puts("Loading: *\b");
tftp_state = STATE_SEND_RRQ;
#ifdef CONFIG_CMD_BOOTEFI
@ -842,9 +889,15 @@ void tftp_start_server(void)
{
tftp_filename[0] = 0;
if (tftp_init_load_addr()) {
eth_halt();
net_set_state(NETLOOP_FAIL);
puts("\nTFTP error: trying to overwrite reserved memory...\n");
return;
}
printf("Using %s device\n", eth_get_name());
printf("Listening for TFTP transfer on %pI4\n", &net_ip);
printf("Load address: 0x%lx\n", load_addr);
printf("Load address: 0x%lx\n", tftp_load_addr);
puts("Loading: *\b");