Ping? It looks like patch 1/2 of this series got into the
recent linux-user pullreq, but this one (2/2) didn't. Do
you want a resend as a standalone patch?
thanks
-- PMM
On 18 July 2016 at 15:36, Peter Maydell <peter.mayd...@linaro.org> wrote:
> The epoll event array which epoll_wait() allocates has a size
> determined by the guest which could potentially be quite large.
> Use g_try_new() rather than alloca() so that we can fail more
> cleanly if the guest hands us an oversize value. (ENOMEM is
> not a documented return value for epoll_wait() but in practice
> some kernel configurations can return it -- see for instance
> sys_oabi_epoll_wait() on ARM.)
>
> This rearrangement includes fixing a bug where we were
> incorrectly passing a negative length to unlock_user() in
> the error-exit codepath.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> linux-user/syscall.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 3552295..721d7b1 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -11035,7 +11035,12 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> goto efault;
> }
>
> - ep = alloca(maxevents * sizeof(struct epoll_event));
> + ep = g_try_new(struct epoll_event, maxevents);
> + if (!ep) {
> + unlock_user(target_ep, arg2, 0);
> + ret = -TARGET_ENOMEM;
> + break;
> + }
>
> switch (num) {
> #if defined(TARGET_NR_epoll_pwait)
> @@ -11053,8 +11058,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> target_set = lock_user(VERIFY_READ, arg5,
> sizeof(target_sigset_t), 1);
> if (!target_set) {
> - unlock_user(target_ep, arg2, 0);
> - goto efault;
> + ret = -TARGET_EFAULT;
> + break;
> }
> target_to_host_sigset(set, target_set);
> unlock_user(target_set, arg5, 0);
> @@ -11082,8 +11087,12 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> target_ep[i].events = tswap32(ep[i].events);
> target_ep[i].data.u64 = tswap64(ep[i].data.u64);
> }
> + unlock_user(target_ep, arg2,
> + ret * sizeof(struct target_epoll_event));
> + } else {
> + unlock_user(target_ep, arg2, 0);
> }
> - unlock_user(target_ep, arg2, ret * sizeof(struct
> target_epoll_event));
> + g_free(ep);
> break;
> }
> #endif
> --
> 1.9.1
