[PATCH 0/2] linux-user: Small fix for copy_file_range

[PATCH 0/2] linux-user: Small fix for copy_file_range

[LemonBoy]

From: Giuseppe Musacchio <thatlemon@gmail.com>

An unwanted sign-extension is currently making the host kernel return EOVERFLOW
when calling copy_file_range with a count of 0xffffffff, despite the host being
a 64bit platform.

The fix is only affecting 32bit targets on 64bit hosts, it's a no-op when the
target bitness matches the host one.

As a bonus add a pretty-printer for copy_file_range syscall.

Giuseppe Musacchio (2):
  linux-user: Add copy_file_range to strace.list
  linux-user: Fix erroneous conversion in copy_file_range

 linux-user/strace.list | 3 +++
 linux-user/syscall.c   | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

-- 
2.30.2

[PATCH 1/2] linux-user: Add copy_file_range to strace.list

[LemonBoy]

From: Giuseppe Musacchio <thatlemon@gmail.com>

Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
---
 linux-user/strace.list | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/linux-user/strace.list b/linux-user/strace.list
index 084048ab96..b81f9964e3 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -1665,3 +1665,6 @@
 #ifdef TARGET_NR_statx
 { TARGET_NR_statx, "statx", NULL, print_statx, NULL },
 #endif
+#ifdef TARGET_NR_copy_file_range
+{ TARGET_NR_copy_file_range, "copy_file_range", "%s(%d,%p,%d,%p,"TARGET_ABI_FMT_lu",%u)", NULL, NULL },
+#endif
-- 
2.30.2

[PATCH 2/2] linux-user: Fix erroneous conversion in copy_file_range

[LemonBoy]

From: Giuseppe Musacchio <thatlemon@gmail.com>

The implicit cast from abi_long to size_t may introduce an intermediate
unwanted sign-extension of the value for 32bit targets running on 64bit
hosts.

Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
---
 linux-user/syscall.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 95d79ddc43..c425dfa278 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -13245,8 +13245,9 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
                 }
                 poutoff = &outoff;
             }
+            /* Do not sign-extend the count parameter. */
             ret = get_errno(safe_copy_file_range(arg1, pinoff, arg3, poutoff,
-                                                 arg5, arg6));
+                                                 (abi_ulong)arg5, arg6));
             if (!is_error(ret) && ret > 0) {
                 if (arg2) {
                     if (put_user_u64(inoff, arg2)) {
-- 
2.30.2

Re: [PATCH 1/2] linux-user: Add copy_file_range to strace.list

[Laurent Vivier]

Le 03/05/2021 à 19:41, LemonBoy a écrit :
> From: Giuseppe Musacchio <thatlemon@gmail.com>
> 
> Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
> ---
>  linux-user/strace.list | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/linux-user/strace.list b/linux-user/strace.list
> index 084048ab96..b81f9964e3 100644
> --- a/linux-user/strace.list
> +++ b/linux-user/strace.list
> @@ -1665,3 +1665,6 @@
>  #ifdef TARGET_NR_statx
>  { TARGET_NR_statx, "statx", NULL, print_statx, NULL },
>  #endif
> +#ifdef TARGET_NR_copy_file_range
> +{ TARGET_NR_copy_file_range, "copy_file_range", "%s(%d,%p,%d,%p,"TARGET_ABI_FMT_lu",%u)", NULL, NULL },
> +#endif
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Re: [PATCH 2/2] linux-user: Fix erroneous conversion in copy_file_range

[Laurent Vivier]

Le 03/05/2021 à 19:41, LemonBoy a écrit :
> From: Giuseppe Musacchio <thatlemon@gmail.com>
> 
> The implicit cast from abi_long to size_t may introduce an intermediate
> unwanted sign-extension of the value for 32bit targets running on 64bit
> hosts.
> 
> Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
> ---
>  linux-user/syscall.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 95d79ddc43..c425dfa278 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -13245,8 +13245,9 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
>                  }
>                  poutoff = &outoff;
>              }
> +            /* Do not sign-extend the count parameter. */
>              ret = get_errno(safe_copy_file_range(arg1, pinoff, arg3, poutoff,
> -                                                 arg5, arg6));
> +                                                 (abi_ulong)arg5, arg6));
>              if (!is_error(ret) && ret > 0) {
>                  if (arg2) {
>                      if (put_user_u64(inoff, arg2)) {
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Re: [PATCH 0/2] linux-user: Small fix for copy_file_range

[Laurent Vivier]

Le 03/05/2021 à 19:41, LemonBoy a écrit :
> From: Giuseppe Musacchio <thatlemon@gmail.com>
> 
> An unwanted sign-extension is currently making the host kernel return EOVERFLOW
> when calling copy_file_range with a count of 0xffffffff, despite the host being
> a 64bit platform.
> 
> The fix is only affecting 32bit targets on 64bit hosts, it's a no-op when the
> target bitness matches the host one.
> 
> As a bonus add a pretty-printer for copy_file_range syscall.
> 
> Giuseppe Musacchio (2):
>   linux-user: Add copy_file_range to strace.list
>   linux-user: Fix erroneous conversion in copy_file_range
> 
>  linux-user/strace.list | 3 +++
>  linux-user/syscall.c   | 3 ++-
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 


Applied to my linux-user-for-6.1 branch.

Thanks,
Laurent