[PATCH] sys_mmap doesn't follow posix.1 when parameter len=0

[PATCH] sys_mmap doesn't follow posix.1 when parameter len=0

[Zhang, Yanmin]

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In IA64 kernel, sys_mmap calls do_mmap2 and do_mmap2 returns addr if
len=0, which means the mmap sys call succeeds.

Posix.1 says:
The mmap() function shall fail if:
[EINVAL] 
The value of len is zero. 

Here is a patch to fix it.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

 <<do_mmap2_zero_len_2.6.12_rc4.patch>> 

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diff -Nraup linux-2.6.12-rc4/arch/ia64/kernel/sys_ia64.c linux-2.6.12-rc4_fix/arch/ia64/kernel/sys_ia64.c
--- linux-2.6.12-rc4/arch/ia64/kernel/sys_ia64.c	2005-05-13 14:14:13.000000000 +0800
+++ linux-2.6.12-rc4_fix/arch/ia64/kernel/sys_ia64.c	2005-05-20 13:10:32.000000000 +0800
@@ -182,13 +182,6 @@ do_mmap2 (unsigned long addr, unsigned l
 		}
 	}
 
-	/*
-	 * A zero mmap always succeeds in Linux, independent of whether or not the
-	 * remaining arguments are valid.
-	 */
-	if (len == 0)
-		goto out;
-
 	/* Careful about overflows.. */
 	len = PAGE_ALIGN(len);
 	if (!len || len > TASK_SIZE) {

Re: [PATCH] sys_mmap doesn't follow posix.1 when parameter len=0

[David Mosberger]

>>>>> On Mon, 23 May 2005 08:47:06 +0800, "Zhang, Yanmin" <yanmin.zhang@intel.com> said:

  Yanmin> In IA64 kernel, sys_mmap calls do_mmap2 and do_mmap2 returns
  Yanmin> addr if len=0, which means the mmap sys call succeeds.

  Yanmin> Posix.1 says: The mmap() function shall fail if: [EINVAL]
  Yanmin> The value of len is zero.

  Yanmin> Here is a patch to fix it.

  Yanmin> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

Looks like Gordon Jin changed mm/mmap.c to be POSIX compliant back in
March 2005 but didn't update the ia64 code.  Looks fine to me.

	--david