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Re: [Qemu-devel] [PATCH v4 5/5] migration: Use strnlen() for fixed-size
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v4 5/5] migration: Use strnlen() for fixed-size string |
Date: |
Sun, 30 Dec 2018 09:34:13 +1100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 |
On 12/29/18 4:33 AM, Philippe Mathieu-Daudé wrote:
> GCC 8 introduced the -Wstringop-overflow, which detect buffer overflow
> by string-modifying functions declared in <string.h>, such strncpy(),
> used in global_state_store_running().
>
> GCC indeed found an incorrect use of strlen(), because this array
> is loaded by VMSTATE_BUFFER(runstate, GlobalState) then parsed
> using qapi_enum_parse which does not get the buffer length.
>
> Use strnlen() which returns sizeof(s->runstate) if the array is not
> NUL-terminated, assert the size is within range, and enforce the array
> to be NUL-terminated to avoid an overflow in qapi_enum_parse().
>
> This fixes:
>
> CC migration/global_state.o
> qemu/migration/global_state.c: In function 'global_state_pre_save':
> qemu/migration/global_state.c:109:15: error: 'strlen' argument 1 declared
> attribute 'nonstring' [-Werror=stringop-overflow=]
> s->size = strlen((char *)s->runstate) + 1;
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> qemu/migration/global_state.c:24:13: note: argument 'runstate' declared here
> uint8_t runstate[100] QEMU_NONSTRING;
> ^~~~~~~~
> cc1: all warnings being treated as errors
> make: *** [qemu/rules.mak:69: migration/global_state.o] Error 1
>
> Suggested-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> migration/global_state.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
Reviewed-by: Richard Henderson <address@hidden>
r~
- [Qemu-devel] [PATCH v4 0/5] Fix strncpy() warnings for GCC8 new -Wstringop-truncation, Philippe Mathieu-Daudé, 2018/12/28
- [Qemu-devel] [PATCH v4 5/5] migration: Use strnlen() for fixed-size string, Philippe Mathieu-Daudé, 2018/12/28
- Re: [Qemu-devel] [PATCH v4 5/5] migration: Use strnlen() for fixed-size string,
Richard Henderson <=
- [Qemu-devel] [PATCH v4 2/5] block/sheepdog: Use QEMU_NONSTRING for non NUL-terminated arrays, Philippe Mathieu-Daudé, 2018/12/28
- [Qemu-devel] [PATCH v4 1/5] qemu/compiler: Define QEMU_NONSTRING, Philippe Mathieu-Daudé, 2018/12/28
- [Qemu-devel] [PATCH v4 4/5] migration: Fix stringop-truncation warning, Philippe Mathieu-Daudé, 2018/12/28
- [Qemu-devel] [PATCH v4 3/5] hw/acpi: Use QEMU_NONSTRING for non NUL-terminated arrays, Philippe Mathieu-Daudé, 2018/12/28