* [PATCH] linux-user: fix target_to_host_timespec64()
@ 2020-08-27 7:04 Laurent Vivier
2020-08-27 9:54 ` Filip Bozuta
0 siblings, 1 reply; 2+ messages in thread
From: Laurent Vivier @ 2020-08-27 7:04 UTC (permalink / raw)
To: qemu-devel; +Cc: Laurent Vivier, Filip Bozuta
in 32 bit mode, drop the padding in tv_nsec. If host is 64bit and target
is 32bit, the padding bytes will be copied from the target and as the
kernel checks the value, the syscall exits with EINVAL.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
linux-user/syscall.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index c82b73e03234..9d7376734ad4 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1253,6 +1253,8 @@ static inline abi_long target_to_host_timespec64(struct timespec *host_ts,
}
__get_user(host_ts->tv_sec, &target_ts->tv_sec);
__get_user(host_ts->tv_nsec, &target_ts->tv_nsec);
+ /* in 32bit mode, this drops the padding */
+ host_ts->tv_nsec = (long)(abi_long)host_ts->tv_nsec;
unlock_user_struct(target_ts, target_addr, 0);
return 0;
}
--
2.26.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] linux-user: fix target_to_host_timespec64()
2020-08-27 7:04 [PATCH] linux-user: fix target_to_host_timespec64() Laurent Vivier
@ 2020-08-27 9:54 ` Filip Bozuta
0 siblings, 0 replies; 2+ messages in thread
From: Filip Bozuta @ 2020-08-27 9:54 UTC (permalink / raw)
To: Laurent Vivier, qemu-devel
On 27.8.20. 09:04, Laurent Vivier wrote:
> in 32 bit mode, drop the padding in tv_nsec. If host is 64bit and target
> is 32bit, the padding bytes will be copied from the target and as the
> kernel checks the value, the syscall exits with EINVAL.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
> linux-user/syscall.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index c82b73e03234..9d7376734ad4 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1253,6 +1253,8 @@ static inline abi_long target_to_host_timespec64(struct timespec *host_ts,
> }
> __get_user(host_ts->tv_sec, &target_ts->tv_sec);
> __get_user(host_ts->tv_nsec, &target_ts->tv_nsec);
> + /* in 32bit mode, this drops the padding */
> + host_ts->tv_nsec = (long)(abi_long)host_ts->tv_nsec;
I tested this with sh4 and the nsec conversion seems to be working fine now.
Just curious, why a double cast is needed '(long)(abi_long)', why not
just '(abi_long)'?
> unlock_user_struct(target_ts, target_addr, 0);
> return 0;
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
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