[v3,1/3] linux: Update the mremap C implementation [BZ #31968]

Message ID 20240717075904.2365688-2-hjl.tools@gmail.com
State Superseded
Delegated to: Adhemerval Zanella Netto
Headers
Series linux: Update the mremap C implementation [BZ #31968] |

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Commit Message

H.J. Lu July 17, 2024, 7:59 a.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 22, 2024, 6:51 p.m. UTC | #1
On 17/07/24 04:59, 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>

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  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 *);
  

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 *);