diff mbox series

[1/3] linux: Update the mremap C implementation [BZ #31968]

Message ID 20240712223147.1809816-2-hjl.tools@gmail.com
State New
Headers show
Series linux: Update the mremap C implementation [BZ #31968] | expand

Commit Message

H.J. Lu July 12, 2024, 10:31 p.m. UTC 
Update the mremap C implementation to support the optional argument for
MREMAP_DONTUNMAP added in Linux 5.7 since it may not always be correct
to implement a variadic function as a non-variadic function on all Linux
targets.  Return MAP_FAILED and set errno to EINVAL for unknown flag bits.
This fixes BZ #31968.

Note: A test must be added when a new flag bit is introduced.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 sysdeps/unix/sysv/linux/mremap.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

Comments

Adhemerval Zanella Netto July 16, 2024, 12:22 p.m. UTC | #1 
On 12/07/24 19:31, H.J. Lu wrote:
> Update the mremap C implementation to support the optional argument for
> MREMAP_DONTUNMAP added in Linux 5.7 since it may not always be correct
> to implement a variadic function as a non-variadic function on all Linux
> targets.  Return MAP_FAILED and set errno to EINVAL for unknown flag bits.
> This fixes BZ #31968.
> 
> Note: A test must be added when a new flag bit is introduced.
> 
> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

I like this version better than revert to assembly code.  I think we should
also update the manual to state the function has variadic arguments and add
a note about the invalid flags, and the MREMAP_FIXED/MREMAP_DONTUNMAP flag.

> ---
>  sysdeps/unix/sysv/linux/mremap.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/mremap.c b/sysdeps/unix/sysv/linux/mremap.c
> index 4f770799c4..1ada5c1f40 100644
> --- a/sysdeps/unix/sysv/linux/mremap.c
> +++ b/sysdeps/unix/sysv/linux/mremap.c
> @@ -20,6 +20,12 @@
>  #include <sysdep.h>
>  #include <stdarg.h>
>  #include <stddef.h>
> +#include <errno.h>
> +
> +#define MREMAP_KNOWN_BITS \
> +  (MREMAP_MAYMOVE \
> +   | MREMAP_FIXED \
> +   | MREMAP_DONTUNMAP)
>  
>  void *
>  __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
> @@ -27,7 +33,13 @@ __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
>    va_list va;
>    void *new_addr = NULL;
>  
> -  if (flags & MREMAP_FIXED)
> +  if (flags & ~(MREMAP_KNOWN_BITS))
> +    {
> +      __set_errno (EINVAL);
> +      return MAP_FAILED;
> +    }
> +
> +  if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP))
>      {
>        va_start (va, flags);
>        new_addr = va_arg (va, void *);
H.J. Lu July 16, 2024, 10:36 p.m. UTC | #2 
On Tue, Jul 16, 2024, 8:22 PM Adhemerval Zanella Netto <
adhemerval.zanella@linaro.org> wrote:

>
>
> On 12/07/24 19:31, H.J. Lu wrote:
> > Update the mremap C implementation to support the optional argument for
> > MREMAP_DONTUNMAP added in Linux 5.7 since it may not always be correct
> > to implement a variadic function as a non-variadic function on all Linux
> > targets.  Return MAP_FAILED and set errno to EINVAL for unknown flag
> bits.
> > This fixes BZ #31968.
> >
> > Note: A test must be added when a new flag bit is introduced.
> >
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
>
> I like this version better than revert to assembly code.  I think we should
> also update the manual to state the function has variadic arguments and add
> a note about the invalid flags, and the MREMAP_FIXED/MREMAP_DONTUNMAP flag.
>

Will add them in v2.


> > ---
> >  sysdeps/unix/sysv/linux/mremap.c | 14 +++++++++++++-
> >  1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/sysdeps/unix/sysv/linux/mremap.c
> b/sysdeps/unix/sysv/linux/mremap.c
> > index 4f770799c4..1ada5c1f40 100644
> > --- a/sysdeps/unix/sysv/linux/mremap.c
> > +++ b/sysdeps/unix/sysv/linux/mremap.c
> > @@ -20,6 +20,12 @@
> >  #include <sysdep.h>
> >  #include <stdarg.h>
> >  #include <stddef.h>
> > +#include <errno.h>
> > +
> > +#define MREMAP_KNOWN_BITS \
> > +  (MREMAP_MAYMOVE \
> > +   | MREMAP_FIXED \
> > +   | MREMAP_DONTUNMAP)
> >
> >  void *
> >  __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
> > @@ -27,7 +33,13 @@ __mremap (void *addr, size_t old_len, size_t new_len,
> int flags, ...)
> >    va_list va;
> >    void *new_addr = NULL;
> >
> > -  if (flags & MREMAP_FIXED)
> > +  if (flags & ~(MREMAP_KNOWN_BITS))
> > +    {
> > +      __set_errno (EINVAL);
> > +      return MAP_FAILED;
> > +    }
> > +
> > +  if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP))
> >      {
> >        va_start (va, flags);
> >        new_addr = va_arg (va, void *);
>
>
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/mremap.c b/sysdeps/unix/sysv/linux/mremap.c
index 4f770799c4..1ada5c1f40 100644
--- a/sysdeps/unix/sysv/linux/mremap.c
+++ b/sysdeps/unix/sysv/linux/mremap.c
@@ -20,6 +20,12 @@ 
 #include <sysdep.h>
 #include <stdarg.h>
 #include <stddef.h>
+#include <errno.h>
+
+#define MREMAP_KNOWN_BITS \
+  (MREMAP_MAYMOVE \
+   | MREMAP_FIXED \
+   | MREMAP_DONTUNMAP)
 
 void *
 __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
@@ -27,7 +33,13 @@  __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...)
   va_list va;
   void *new_addr = NULL;
 
-  if (flags & MREMAP_FIXED)
+  if (flags & ~(MREMAP_KNOWN_BITS))
+    {
+      __set_errno (EINVAL);
+      return MAP_FAILED;
+    }
+
+  if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP))
     {
       va_start (va, flags);
       new_addr = va_arg (va, void *);