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Re: [Qemu-devel] [PATCH v2 1/5] linux-user: avoid string truncation warn
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/5] linux-user: avoid string truncation warnings in uname field copying |
Date: |
Fri, 12 Apr 2019 14:28:41 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 12/04/2019 14:16, Daniel P. Berrangé wrote:
> In file included from /usr/include/string.h:494,
> from include/qemu/osdep.h:101,
> from linux-user/uname.c:20:
> In function ‘strncpy’,
> inlined from ‘sys_uname’ at linux-user/uname.c:94:3:
> /usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
> output may be truncated copying 64 bytes from a string of length 64
> [-Wstringop-truncation]
> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos
> (__dest));
> |
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> We don't care where the NUL terminator in the original uname
> field was. It suffices to copy the entire original field and
> simply force a NUL terminator at the end of the new field.
>
> Signed-off-by: Daniel P. Berrangé <address@hidden>
> ---
> linux-user/uname.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/uname.c b/linux-user/uname.c
> index 313b79dbad..3dff33effe 100644
> --- a/linux-user/uname.c
> +++ b/linux-user/uname.c
> @@ -73,7 +73,7 @@ const char *cpu_to_uname_machine(void *cpu_env)
> #define COPY_UTSNAME_FIELD(dest, src) \
> do { \
> /* __NEW_UTS_LEN doesn't include terminating null */ \
> - (void) strncpy((dest), (src), __NEW_UTS_LEN); \
> + memcpy((dest), (src), MIN(sizeof(src), __NEW_UTS_LEN)); \
If we use sizeof(), I think we should use it for both:
MIN(sizeof(dest), sizeof(src))
Thanks,
Laurent
- [Qemu-devel] [PATCH v2 0/5] misc set of fixes for warnings under GCC 9, Daniel P . Berrangé, 2019/04/12
- [Qemu-devel] [PATCH v2 1/5] linux-user: avoid string truncation warnings in uname field copying, Daniel P . Berrangé, 2019/04/12
- Re: [Qemu-devel] [PATCH v2 1/5] linux-user: avoid string truncation warnings in uname field copying,
Laurent Vivier <=
- [Qemu-devel] [PATCH v2 2/5] linux-user: avoid string truncation warnings in elf field copying, Daniel P . Berrangé, 2019/04/12
- [Qemu-devel] [PATCH v2 3/5] sockets: avoid string truncation warnings when copying UNIX path, Daniel P . Berrangé, 2019/04/12
- [Qemu-devel] [PATCH v2 4/5] hw/usb: avoid format truncation warning when formatting port name, Daniel P . Berrangé, 2019/04/12
- [Qemu-devel] [PATCH v2 5/5] qxl: avoid unaligned pointer reads/writes, Daniel P . Berrangé, 2019/04/12