[PATCH] mmap.2: Add EOVERFLOW

* [PATCH] mmap.2: Add EOVERFLOW
@ 2012-11-12 10:56 chrubis-AlSwsSmVLrQ
       [not found] ` <20121112105632.GB6764-J5syqNJeCN7twjQa/ONI9g@public.gmane.org>
  0 siblings, 1 reply; 2+ messages in thread
From: chrubis-AlSwsSmVLrQ @ 2012-11-12 10:56 UTC (permalink / raw)
  To: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w; +Cc: linux-man-u79uwXL29TY76Z2rM5mHXA

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This patch adds EOVERFLOW and conditions needed to
trigger it into mmap.2 man page.

-- 
Cyril Hrubis
chrubis-AlSwsSmVLrQ@public.gmane.org

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>From e656978560e317b95a8315b9556690e8c03917f2 Mon Sep 17 00:00:00 2001
From: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
Date: Wed, 7 Nov 2012 11:52:55 +0100
Subject: [PATCH 1/2] mmap.2: Add EOVERFLOW to ERRORS.

The overflow could be triggered on 32 bit arch
with large file extension (i.e. 64 bit off_t)
if number of pages used for len plus number of
pages used for offset would overflow 32 bit
unsigned long.

In this case we would hit this line from do_mmap_pgoff:

...
	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
		return -EOVERFLOW;
...

Note that if the offset is too big (would overflow
unsigned long in number of pages itself) you would hit
EINVAL first.

The code to trigger this condition could be
seen in LTP git repo in:

open_posix_testsuite/conformance/interfaces/mmap/31-1.c

Signed-off-by: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
---
 man2/mmap.2 |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/man2/mmap.2 b/man2/mmap.2
index 042b833..29fcc3d 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -470,6 +470,11 @@ was mounted no-exec.
 was set but the object specified by
 .I fd
 is open for writing.
+.TP
+.B EOVERFLOW
+happens on 32 bit architecture together with large file extension (i.e. using
+64 bit off_t) when number of pages used for length plus number of pages used
+for offset would overflow unsigned long (32 bits)
 .LP
 Use of a mapped region can result in these signals:
 .TP
-- 
1.7.8.6


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>From e656978560e317b95a8315b9556690e8c03917f2 Mon Sep 17 00:00:00 2001
From: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
Date: Wed, 7 Nov 2012 11:52:55 +0100
Subject: [PATCH 1/2] mmap.2: Add EOVERFLOW to ERRORS.

The overflow could be triggered on 32 bit arch
with large file extension (i.e. 64 bit off_t)
if number of pages used for len plus number of
pages used for offset would overflow 32 bit
unsigned long.

In this case we would hit this line from do_mmap_pgoff:

...
	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
		return -EOVERFLOW;
...

Note that if the offset is too big (would overflow
unsigned long in number of pages itself) you would hit
EINVAL first.

The code to trigger this condition could be
seen in LTP git repo in:

open_posix_testsuite/conformance/interfaces/mmap/31-1.c

Signed-off-by: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>
---
 man2/mmap.2 |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/man2/mmap.2 b/man2/mmap.2
index 042b833..29fcc3d 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -470,6 +470,11 @@ was mounted no-exec.
 was set but the object specified by
 .I fd
 is open for writing.
+.TP
+.B EOVERFLOW
+happens on 32 bit architecture together with large file extension (i.e. using
+64 bit off_t) when number of pages used for length plus number of pages used
+for offset would overflow unsigned long (32 bits)
 .LP
 Use of a mapped region can result in these signals:
 .TP
-- 
1.7.8.6


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