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Subject[PATCH 1/5] pagemap: Modify add_to_pagemap to use copy_to_user instead of put_user.
While fiddling with pagemap, I discovered a bug in add_to_pagemap.
When it is copying an entry that is not at the end of the buffer, it
uses put_user to copy a u64 into a char* buffer. The problem is that
put_user determines how much to copy based on the size of the
*destination*, not the source, so it only copied one byte. To fix
this, I replaced the call to put_user with a call to copy_to_user, as
is used when copying the last (possibly partial) PFN into the buffer.
From 3240be0d489e914bbb5a559c21413e39889934ef Mon Sep 17 00:00:00 2001
From: Thomas Tuttle <ttuttle@google.com>
Date: Thu, 5 Jun 2008 09:37:24 -0400
Subject: [PATCH] Modified add_to_pagemap to use copy_to_user instead of put_user.
Using put_user only copies the low byte of the pagecount, because the
destination buffer is a char*.

Signed-off-by: Thomas Tuttle <ttuttle@google.com>
---
fs/proc/task_mmu.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 88717c0..9915202 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -531,7 +531,7 @@ static int add_to_pagemap(unsigned long addr, u64 pfn,
return PM_END_OF_BUFFER;
}

- if (put_user(pfn, pm->out))
+ if (copy_to_user(pm->out, &pfn, PM_ENTRY_BYTES))
return -EFAULT;
pm->out += PM_ENTRY_BYTES;
return 0;
--
1.5.3.6
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