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Re: [Qemu-devel] [PATCH] linux-user: fix "may be used uninitialized" war
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: fix "may be used uninitialized" warnings |
Date: |
Wed, 6 Mar 2019 13:45:20 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 05/03/2019 16:15, Marc-André Lureau wrote:
> Fixes:
>
> /home/elmarco/src/qemu/linux-user/syscall.c: In function ‘do_ioctl_rt’:
> /home/elmarco/src/qemu/linux-user/syscall.c:4773:9: error: ‘host_rt_dev_ptr’
> may be used uninitialized in this function [-Werror=maybe-uninitialized]
> if (*host_rt_dev_ptr != 0) {
> ^~~~~~~~~~~~~~~~
> /home/elmarco/src/qemu/linux-user/syscall.c:4774:9: error:
> ‘target_rt_dev_ptr’ may be used uninitialized in this function
> [-Werror=maybe-uninitialized]
> unlock_user((void *)*host_rt_dev_ptr,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> *target_rt_dev_ptr, 0);
> ~~~~~~~~~~~~~~~~~~~~~~
>
> Based on previous discussion from patch "linux-users/syscall: make
> do_ioctl_rt safer" by Alex Bennée.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
> linux-user/syscall.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 5bbb72f3d5..a15340b302 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4723,8 +4723,8 @@ static abi_long do_ioctl_rt(const IOCTLEntry *ie,
> uint8_t *buf_temp,
> const int *dst_offsets, *src_offsets;
> int target_size;
> void *argptr;
> - abi_ulong *target_rt_dev_ptr;
> - unsigned long *host_rt_dev_ptr;
> + abi_ulong *target_rt_dev_ptr = NULL;
> + unsigned long *host_rt_dev_ptr = NULL;
> abi_long ret;
> int i;
>
> @@ -4770,6 +4770,9 @@ static abi_long do_ioctl_rt(const IOCTLEntry *ie,
> uint8_t *buf_temp,
> unlock_user(argptr, arg, 0);
>
> ret = get_errno(safe_ioctl(fd, ie->host_cmd, buf_temp));
> +
> + assert(host_rt_dev_ptr != NULL);
> + assert(target_rt_dev_ptr != NULL);
> if (*host_rt_dev_ptr != 0) {
> unlock_user((void *)*host_rt_dev_ptr,
> *target_rt_dev_ptr, 0);
>
Reviewed-by: Laurent Vivier <address@hidden>