Re: [PATCH] linux-user: fix O_NONBLOCK in signalfd4() and eventfd2() syscalls

[Helge Deller]

Dear qemu-stable,

can you please consider adding this patch to the qemu-stable branch.
Upstream commit 78721301138114cf37fb179a6cf73a27c1b3a927
Thanks,
Helge


On 2/13/21 8:16 PM, Laurent Vivier wrote:
> Le 10/02/2021 à 07:12, Helge Deller a écrit :
> > On the hppa target userspace binaries may call signalfd4() and
> > eventfd2() with an old TARGET_O_NONBLOCK value of 000200004 instead of
> > 000200000 for the "mask" syscall parameter, in which case the current
> > emulation doesn't handle the translation to the native O_NONBLOCK value
> > correctly.
> >
> > The 0x04 bit is not masked out before the new O_NONBLOCK bit is set and
> > as such when calling the native syscall errors out with EINVAL.
> >
> > Fix this by introducing TARGET_O_NONBLOCK_MASK which is used to mask off
> > all possible bits. This define defaults to TARGET_O_NONBLOCK when not
> > defined otherwise, so for all other targets the implementation will
> > behave as before.
> >
> > This patch needs to be applied on top of my previous two patches.
> >
> > Bug was found and patch was verified by using qemu-hppa as debian buildd
> > server on x86_64.
> >
> > Signed-off-by: Helge Deller <deller@gmx.de>
> >
> > ---
> >
> > diff --git a/linux-user/hppa/target_fcntl.h b/linux-user/hppa/target_fcntl.h
> > index 08e3a4fcb0..4eb0ec98e2 100644
> > --- a/linux-user/hppa/target_fcntl.h
> > +++ b/linux-user/hppa/target_fcntl.h
> > @@ -9,6 +9,7 @@
> >   #define HPPA_TARGET_FCNTL_H
> >
> >   #define TARGET_O_NONBLOCK    000200000
> > +#define TARGET_O_NONBLOCK_MASK 000200004 /* includes old HP-UX NDELAY flag */
> >   #define TARGET_O_APPEND      000000010
> >   #define TARGET_O_CREAT       000000400 /* not fcntl */
> >   #define TARGET_O_EXCL        000002000 /* not fcntl */
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index 27adee908e..3031aa342f 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -273,6 +273,11 @@ static type name (type1 arg1,type2 arg2,type3 arg3,type4 
> > arg4,type5 arg5,  \
> >   #define TARGET_NR__llseek TARGET_NR_llseek
> >   #endif
> >
> > +/* some platforms need to mask more bits than just TARGET_O_NONBLOCK */
> > +#ifndef TARGET_O_NONBLOCK_MASK
> > +#define TARGET_O_NONBLOCK_MASK TARGET_O_NONBLOCK
> > +#endif
> > +
> >   #define __NR_sys_gettid __NR_gettid
> >   _syscall0(int, sys_gettid)
> >
> > @@ -7719,7 +7724,7 @@ static abi_long do_signalfd4(int fd, abi_long mask, int 
> > flags)
> >       sigset_t host_mask;
> >       abi_long ret;
> >
> > -    if (flags & ~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC)) {
> > +    if (flags & ~(TARGET_O_NONBLOCK_MASK | TARGET_O_CLOEXEC)) {
> >           return -TARGET_EINVAL;
> >       }
> >       if (!lock_user_struct(VERIFY_READ, target_mask, mask, 1)) {
> > @@ -12508,7 +12513,7 @@ static abi_long do_syscall1(void *cpu_env, int num, 
> > abi_long arg1,
> >   #if defined(TARGET_NR_eventfd2)
> >       case TARGET_NR_eventfd2:
> >       {
> > -        int host_flags = arg2 & (~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC));
> > +        int host_flags = arg2 & (~(TARGET_O_NONBLOCK_MASK | TARGET_O_CLOEXEC));
> >           if (arg2 & TARGET_O_NONBLOCK) {
> >               host_flags |= O_NONBLOCK;
> >           }
>
> Applied to my linux-user-for-6.0 branch.
>
> Thanks,
> Laurent