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Re: [Qemu-devel] [PATCH] linux-user: Fix conversion of sigevent argument
From: |
Riku Voipio |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Fix conversion of sigevent argument to timer_create |
Date: |
Tue, 12 Aug 2014 10:37:57 +0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sat, Aug 09, 2014 at 03:42:32PM +0100, Peter Maydell wrote:
> There were a number of bugs in the conversion of the sigevent
> argument to timer_create from target to host format:
> * signal number not converted from target to host
> * thread ID not copied across
> * sigev_value not copied across
> * we never unlocked the struct when we were done
>
> Between them, these problems meant that SIGEV_THREAD_ID
> timers (and the glibc-implemented SIGEV_THREAD timers which
> depend on them) didn't work.
>
> Fix these problems and clean up the code a little by pulling
> the struct conversion out into its own function, in line with
> how we convert various other structs. This allows the test
> program in bug LP:1042388 to run.
>
> Signed-off-by: Peter Maydell <address@hidden>
Thanks, applied to linux-user - replacing Erik's patch.
Riku
> ---
> Riku: this is going to conflict with and supersede Erik's oneliner
> patch which adds the unlock_user_struct() (I'm afraid I forgot about
> that when I was writing this and independently re-fixed the bug),
> so it might be simplest to drop that from the linux-user queue if
> you apply this instead. Otherwise if that patch makes it to master
> I'll rebase and resend this one at that point.
>
> linux-user/syscall.c | 38 ++++++++++++++++++++++++++++++--------
> 1 file changed, 30 insertions(+), 8 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index a50229d..4ce7455 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4914,6 +4914,32 @@ static inline abi_long
> host_to_target_itimerspec(abi_ulong target_addr,
> return 0;
> }
>
> +static inline abi_long target_to_host_sigevent(struct sigevent *host_sevp,
> + abi_ulong target_addr)
> +{
> + struct target_sigevent *target_sevp;
> +
> + if (!lock_user_struct(VERIFY_READ, target_sevp, target_addr, 1)) {
> + return -TARGET_EFAULT;
> + }
> +
> + /* This union is awkward on 64 bit systems because it has a 32 bit
> + * integer and a pointer in it; we follow the conversion approach
> + * used for handling sigval types in signal.c so the guest should get
> + * the correct value back even if we did a 64 bit byteswap and it's
> + * using the 32 bit integer.
> + */
> + host_sevp->sigev_value.sival_ptr =
> + (void *)(uintptr_t)tswapal(target_sevp->sigev_value.sival_ptr);
> + host_sevp->sigev_signo =
> + target_to_host_signal(tswap32(target_sevp->sigev_signo));
> + host_sevp->sigev_notify = tswap32(target_sevp->sigev_notify);
> + host_sevp->_sigev_un._tid = tswap32(target_sevp->_sigev_un._tid);
> +
> + unlock_user_struct(target_sevp, target_addr, 1);
> + return 0;
> +}
> +
> #if defined(TARGET_NR_stat64) || defined(TARGET_NR_newfstatat)
> static inline abi_long host_to_target_stat64(void *cpu_env,
> abi_ulong target_addr,
> @@ -9413,7 +9439,6 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> /* args: clockid_t clockid, struct sigevent *sevp, timer_t *timerid
> */
>
> struct sigevent host_sevp = { {0}, }, *phost_sevp = NULL;
> - struct target_sigevent *ptarget_sevp;
> struct target_timer_t *ptarget_timer;
>
> int clkid = arg1;
> @@ -9425,14 +9450,11 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> timer_t *phtimer = g_posix_timers + timer_index;
>
> if (arg2) {
> - if (!lock_user_struct(VERIFY_READ, ptarget_sevp, arg2, 1)) {
> - goto efault;
> - }
> -
> - host_sevp.sigev_signo = tswap32(ptarget_sevp->sigev_signo);
> - host_sevp.sigev_notify = tswap32(ptarget_sevp->sigev_notify);
> -
> phost_sevp = &host_sevp;
> + ret = target_to_host_sigevent(phost_sevp, arg2);
> + if (ret != 0) {
> + break;
> + }
> }
>
> ret = get_errno(timer_create(clkid, phost_sevp, phtimer));
> --
> 1.9.1
>