util/cbmem: Fix out of bounds access
Building cbmem with ASan
$ CC=gcc-5 CFLAGS="-O1 -g -fsanitize=address -fno-omit-frame-pointer" LDFLAGS="-fsanitize=address" make
it sometimes finds a heap-buffer-overflow, while dumping the CBMEM
console.
$ sudo ./cbmem -c
=================================================================
==11208==ERROR: AddressSanitizer: heap-buffer-overflow on address 0xb5d5782b at pc 0x0804a4d7 bp 0xbfe23bc8 sp 0xbfe23bbc
WRITE of size 1 at 0xb5d5782b thread T0
#0 0x804a4d6 in dump_console /home/joey/src/coreboot/util/cbmem/cbmem.c:553
#1 0x804a4d6 in main /home/joey/src/coreboot/util/cbmem/cbmem.c:1134
#2 0xb70a3a62 in __libc_start_main (/lib/i386-linux-gnu/i686/cmov/libc.so.6+0x19a62)
#3 0x8048cf0 (/home/joey/src/coreboot/util/cbmem/cbmem+0x8048cf0)
0xb5d5782b is located 50 bytes to the right of 131065-byte region [0xb5d37800,0xb5d577f9)
allocated by thread T0 here:
#0 0xb72c64ce in __interceptor_malloc (/usr/lib/i386-linux-gnu/libasan.so.2+0x924ce)
#1 0x804a407 in dump_console /home/joey/src/coreboot/util/cbmem/cbmem.c:542
#2 0x804a407 in main /home/joey/src/coreboot/util/cbmem/cbmem.c:1134
#3 0xb70a3a62 in __libc_start_main (/lib/i386-linux-gnu/i686/cmov/libc.so.6+0x19a62)
SUMMARY: AddressSanitizer: heap-buffer-overflow /home/joey/src/coreboot/util/cbmem/cbmem.c:553 dump_console
Shadow bytes around the buggy address:
0x36baaeb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x36baaec0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x36baaed0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x36baaee0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x36baaef0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
=>0x36baaf00: fa fa fa fa fa[fa]fa fa fa fa fa fa fa fa fa fa
0x36baaf10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36baaf20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36baaf30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36baaf40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36baaf50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
==11208==ABORTING
Fix up commit 06b13a37 (cbmem: Terminate the cbmem console at the cursor
position.) by reverting setting the cursor to 0.
Change-Id: Id614a8e0f1a202671dd091f825d826a17176bfcc
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/10572
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/util/cbmem/cbmem.c b/util/cbmem/cbmem.c
index 3c7f49b..d8c6145 100644
--- a/util/cbmem/cbmem.c
+++ b/util/cbmem/cbmem.c
@@ -685,7 +685,7 @@
*/
if (size > cursor)
size = cursor;
- console_c = malloc(size + 1);
+ console_c = calloc(1, size + 1);
unmap_memory();
if (!console_c) {
fprintf(stderr, "Not enough memory for console.\n");
@@ -695,8 +695,6 @@
console_p = map_memory_size((unsigned long)console.cbmem_addr,
size + sizeof(size) + sizeof(cursor), 1);
memcpy(console_c, console_p + 8, size);
- console_c[size] = 0;
- console_c[cursor] = 0;
printf("%s\n", console_c);
if (size < cursor)