Re: [Qemu-devel] [PATCH] qemu-pr-helper: check the return value of fcntl in do_pr_out

[lizhengui]

If the fd is invalid or interrupted by signal.

-----邮件原件-----
发件人: Paolo Bonzini [mailto:address@hidden 
发送时间: 2019年3月21日 18:38
收件人: lizhengui; address@hidden; address@hidden; address@hidden
抄送: address@hidden; address@hidden; Fangyi (C); wangjie (P)
主题: Re: [PATCH] qemu-pr-helper: check the return value of fcntl in do_pr_out

On 20/03/19 15:07, Zhengui li wrote:
> The function fcntl maybe return -1, which is not a unsigned type.
> Unsigned type or Negative values should not do bitwise operator with 
> O_ACCMODE.

Did you actually find a case in which the fcntl can fail?

Paolo

> Signed-off-by: Zhengui li <address@hidden>
> ---
>  scsi/qemu-pr-helper.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c index 
> e7af637..fcbe4d9 100644
> --- a/scsi/qemu-pr-helper.c
> +++ b/scsi/qemu-pr-helper.c
> @@ -551,8 +551,14 @@ static int do_pr_out(int fd, const uint8_t *cdb, uint8_t 
> *sense,
>                       const uint8_t *param, int sz)  {
>      int resp_sz;
> +    int flags;
>  
> -    if ((fcntl(fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {
> +    flags = fcntl(fd, F_GETFL);
> +    if (flags < 0) {
> +        return -1;
> +    }
> +
> +    if (((unsigned int) flags & O_ACCMODE) == O_RDONLY) {
>          scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
>          return CHECK_CONDITION;
>      }
>