Re: [U-Boot] [U-Boot, v2, 10/10] gpt: harden set_gpt_info() against non NULL-terminated strings

On Tue, Jul 04, 2017 at 11:19:46AM -0700, Alison Chaiken wrote:

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

Applied to u-boot/master, thanks!