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[PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc

dinglimin posted 1 patch 9 months ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20240226090628.1986-1-dinglimin@cmss.chinamobile.com
Maintainers: "Alex Bennée" <alex.bennee@linaro.org>
semihosting/uaccess.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
[PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
Posted by dinglimin 9 months ago 
Signed-off-by: dinglimin <dinglimin@cmss.chinamobile.com>
---
 semihosting/uaccess.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/semihosting/uaccess.c b/semihosting/uaccess.c
index dc587d73bc..7788ead9b2 100644
--- a/semihosting/uaccess.c
+++ b/semihosting/uaccess.c
@@ -14,10 +14,10 @@
 void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
                         target_ulong len, bool copy)
 {
-    void *p = malloc(len);
+    void *p = g_try_malloc(len);
     if (p && copy) {
         if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
-            free(p);
+            g_free(p);
             p = NULL;
         }
     }
@@ -87,5 +87,5 @@ void uaccess_unlock_user(CPUArchState *env, void *p,
     if (len) {
         cpu_memory_rw_debug(env_cpu(env), addr, p, len, 1);
     }
-    free(p);
+    g_free(p);
 }
-- 
2.30.0.windows.2
Re: [PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
Posted by Zhao Liu 9 months ago 
On Mon, Feb 26, 2024 at 05:06:28PM +0800, dinglimin wrote:
> Date: Mon, 26 Feb 2024 17:06:28 +0800
> From: dinglimin <dinglimin@cmss.chinamobile.com>
> Subject: [PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
> X-Mailer: git-send-email 2.30.0.windows.2
> 
> Signed-off-by: dinglimin <dinglimin@cmss.chinamobile.com>
> ---
>  semihosting/uaccess.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Also cc Michael and qemu-trivial@nongnu.org.
I understand the simple cleanup can cc qemu-trivial@nongnu.org. ;-)

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

> 
> diff --git a/semihosting/uaccess.c b/semihosting/uaccess.c
> index dc587d73bc..7788ead9b2 100644
> --- a/semihosting/uaccess.c
> +++ b/semihosting/uaccess.c
> @@ -14,10 +14,10 @@
>  void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
>                          target_ulong len, bool copy)
>  {
> -    void *p = malloc(len);
> +    void *p = g_try_malloc(len);
>      if (p && copy) {
>          if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
> -            free(p);
> +            g_free(p);
>              p = NULL;
>          }
>      }
> @@ -87,5 +87,5 @@ void uaccess_unlock_user(CPUArchState *env, void *p,
>      if (len) {
>          cpu_memory_rw_debug(env_cpu(env), addr, p, len, 1);
>      }
> -    free(p);
> +    g_free(p);
>  }
> -- 
> 2.30.0.windows.2
Re: [PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
Posted by Philippe Mathieu-Daudé 9 months ago 
Hi,

On 26/2/24 10:06, dinglimin wrote:
> Signed-off-by: dinglimin <dinglimin@cmss.chinamobile.com>
> ---
>   semihosting/uaccess.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/semihosting/uaccess.c b/semihosting/uaccess.c
> index dc587d73bc..7788ead9b2 100644
> --- a/semihosting/uaccess.c
> +++ b/semihosting/uaccess.c
> @@ -14,10 +14,10 @@
>   void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
>                           target_ulong len, bool copy)
>   {
> -    void *p = malloc(len);
> +    void *p = g_try_malloc(len);
>       if (p && copy) {
>           if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
> -            free(p);
> +            g_free(p);
>               p = NULL;
>           }
>       }

This seems dangerous, now all users of uaccess_lock_user() must
use g_free(), in particular lock_user_string() which is used more
than a hundred of times:

$ git grep -w lock_user_string | wc -l
      116

> @@ -87,5 +87,5 @@ void uaccess_unlock_user(CPUArchState *env, void *p,
>       if (len) {
>           cpu_memory_rw_debug(env_cpu(env), addr, p, len, 1);
>       }
> -    free(p);
> +    g_free(p);
>   }
Re: [PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
Posted by Peter Maydell 9 months ago 
On Mon, 26 Feb 2024 at 09:49, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> Hi,
>
> On 26/2/24 10:06, dinglimin wrote:
> > Signed-off-by: dinglimin <dinglimin@cmss.chinamobile.com>
> > ---
> >   semihosting/uaccess.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/semihosting/uaccess.c b/semihosting/uaccess.c
> > index dc587d73bc..7788ead9b2 100644
> > --- a/semihosting/uaccess.c
> > +++ b/semihosting/uaccess.c
> > @@ -14,10 +14,10 @@
> >   void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
> >                           target_ulong len, bool copy)
> >   {
> > -    void *p = malloc(len);
> > +    void *p = g_try_malloc(len);
> >       if (p && copy) {
> >           if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
> > -            free(p);
> > +            g_free(p);
> >               p = NULL;
> >           }
> >       }
>
> This seems dangerous, now all users of uaccess_lock_user() must
> use g_free(), in particular lock_user_string() which is used more
> than a hundred of times:

Users of lock_user_string() and other lock_user() functions are
supposed to unlock via unlock_user(); if they directly call either
free() or g_free() they have a bug.

-- PMM
Re: [PATCH] semihosting/uaccess.c: Replaced a malloc call with g_malloc
Posted by Daniel P. Berrangé 9 months ago 
On Mon, Feb 26, 2024 at 10:48:14AM +0100, Philippe Mathieu-Daudé wrote:
> Hi,
> 
> On 26/2/24 10:06, dinglimin wrote:
> > Signed-off-by: dinglimin <dinglimin@cmss.chinamobile.com>
> > ---
> >   semihosting/uaccess.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/semihosting/uaccess.c b/semihosting/uaccess.c
> > index dc587d73bc..7788ead9b2 100644
> > --- a/semihosting/uaccess.c
> > +++ b/semihosting/uaccess.c
> > @@ -14,10 +14,10 @@
> >   void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
> >                           target_ulong len, bool copy)
> >   {
> > -    void *p = malloc(len);
> > +    void *p = g_try_malloc(len);
> >       if (p && copy) {
> >           if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
> > -            free(p);
> > +            g_free(p);
> >               p = NULL;
> >           }
> >       }
> 
> This seems dangerous, now all users of uaccess_lock_user() must
> use g_free(), in particular lock_user_string() which is used more
> than a hundred of times:

This is not true for many years now.

GLib is hardcoded to always use the system allocator, so g_malloc
can be freely mixed with free, and vica-verca.

Using 'g_free' is stylistically preferred, but not functionally
required.

> 
> $ git grep -w lock_user_string | wc -l
>      116
> 
> > @@ -87,5 +87,5 @@ void uaccess_unlock_user(CPUArchState *env, void *p,
> >       if (len) {
> >           cpu_memory_rw_debug(env_cpu(env), addr, p, len, 1);
> >       }
> > -    free(p);
> > +    g_free(p);
> >   }
> 
> 

With regards,
Daniel
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