[U-Boot] [PATCH] core: ofnode: Fix ASAN-reported stack-buffer-overflow in of_get_address

[Simon Glass]

On Sat, 9 Mar 2019 at 09:27, Eugeniu Rosca <roscaeugeniu at gmail.com> wrote:
>
> v2019.04-rc3 sandbox U-Boot fails to boot when compiled with
>  -fsanitize=address and linked against -lasan, reporting [1].
>
> Git bisecting shows that the issue is contributed by v2019.01 commit
> 1678754f5e2c ("core: ofnode: Fix ofnode_get_addr_index function").
>
> The root cause seems to be the mismatch between sizeof(u64) and
> sizeof(fdt_size_t) on sandbox. Luckily, thanks to the fact that the
> size argument of both of_get_address() and fdtdec_get_addr_size_fixed()
> is optional, we can pass NULL in its place, avoiding the problem.
>
> [1] Backtrace reported by ASAN (gcc 8.1.0):
>
> $> ./u-boot -d arch/sandbox/dts/sandbox.dtb
> [..]
> =================================================================
> ==10998==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffcc2331140 at pc 0x0000004eeeb0 bp 0x7ffcc2330f80 sp 0x7ffcc2330f70
> WRITE of size 8 at 0x7ffcc2331140 thread T0
>     #0 0x4eeeaf in of_get_address drivers/core/of_addr.c:154
>     #1 0x4f7441 in ofnode_get_addr_index drivers/core/ofnode.c:263
>     #2 0x5b2a78 in sb_eth_ofdata_to_platdata drivers/net/sandbox.c:422
>     #3 0x4dccd8 in device_probe drivers/core/device.c:407
>     #4 0x753170 in eth_initialize net/eth-uclass.c:428
>     #5 0x47d9bf in initr_net common/board_r.c:557
>     #6 0x6bcfa7 in initcall_run_list lib/initcall.c:30
>     #7 0x47e1fe in board_init_r common/board_r.c:859
>     #8 0x4060e5 in main arch/sandbox/cpu/start.c:356
>     #9 0x7fb8d135482f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
>     #10 0x40a3a8 in _start (/path/to/u-boot/u-boot+0x40a3a8)
>
> Address 0x7ffcc2331140 is located in stack of thread T0 at offset 32 in frame
>     #0 0x4f72b8 in ofnode_get_addr_index drivers/core/ofnode.c:255
>
>   This frame has 3 object(s):
>     [32, 36) 'size' <== Memory access at offset 32 partially overflows this variable
>     [96, 100) 'flags'
>     [160, 168) 'node'
> HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
>       (longjmp and C++ exceptions *are* supported)
> SUMMARY: AddressSanitizer: stack-buffer-overflow drivers/core/of_addr.c:154 in of_get_address
> Shadow bytes around the buggy address:
>   0x10001845e1d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x10001845e1e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x10001845e1f0: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
>   0x10001845e200: 04 f2 f2 f2 f2 f2 f2 f2 04 f2 f2 f2 f2 f2 f2 f2
>   0x10001845e210: 04 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00
> =>0x10001845e220: 00 00 00 00 f1 f1 f1 f1[04]f2 f2 f2 f2 f2 f2 f2
>   0x10001845e230: 04 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f3 f3 f3 f3
>   0x10001845e240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x10001845e250: 00 00 00 00 f1 f1 f1 f1 00 00 f2 f2 f3 f3 f3 f3
>   0x10001845e260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
>   0x10001845e270: f1 f1 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00
> 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
>   Freed heap region:       fd
>   Stack left redzone:      f1
>   Stack mid redzone:       f2
>   Stack right redzone:     f3
>   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
>   Left alloca redzone:     ca
>   Right alloca redzone:    cb
> ==10998==ABORTING
>
> 'To' list:
>  git log --since=1year drivers/core/ofnode.c | grep "\-by: .*@" | \
>      sed 's/.*-by: //' | sort | uniq -c | sort -rn
>      10 Simon Glass <sjg at chromium.org>
>       3 Mario Six <mario.six at gdsys.cc>
>       2 Martin Fuzzey <mfuzzey at parkeon.com>
>       2 Marek Vasut <marek.vasut+renesas at gmail.com>
>       1 Tom Rini <trini at konsulko.com>
>       1 Masahiro Yamada <yamada.masahiro at socionext.com>
>       1 Keerthy <j-keerthy at ti.com>
>       1 Jens Wiklander <jens.wiklander at linaro.org>
>       1 Bin Meng <bmeng.cn at gmail.com>
>
> Fixes: 1678754f5e2c ("core: ofnode: Fix ofnode_get_addr_index function")
> Signed-off-by: Eugeniu Rosca <erosca at de.adit-jv.com>
> ---
>  drivers/core/ofnode.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)

Reviewed-by: Simon Glass <sjg at chromium.org>