Re: [PATCH 2/2] linux-user/main: Check errno when getting AT_EXECFD

[Richard Henderson <richard.henderson@linaro.org>]

On 7/21/24 19:08, Vivian Wang wrote:
> It's possible for AT_EXECFD to end up with a valid value of 0. Check
> errno when using qemu_getauxval instead of return value to handle this
> case.
> 
> Not handling this case leads to a confusing condition where the
> executable ends up as fd 0, i.e. stdin.
> 
> Signed-off-by: Vivian Wang <uwu@dram.page>
> Fixes: 0b959cf5e4cc ("linux-user: Use qemu_getauxval for AT_EXECFD")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2448
> ---
>   linux-user/main.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 7d3cf45fa9..8143a0d4b0 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -755,8 +755,9 @@ int main(int argc, char **argv, char **envp)
>       /*
>        * Manage binfmt-misc open-binary flag
>        */
> +    errno = 0;
>       execfd = qemu_getauxval(AT_EXECFD);
> -    if (execfd == 0) {
> +    if (errno != 0) {
>           execfd = open(exec_path, O_RDONLY);
>           if (execfd < 0) {
>               printf("Error while loading %s: %s\n", exec_path, strerror(errno));

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~