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pagemap: fix bug in add_to_pagemap, require aligned-length reads of /proc/pid/pagemap 

Fix a bug in add_to_pagemap.  Previously, since pm->out was a char *,
put_user was only copying 1 byte of every PFN, resulting in the top 7
bytes of each PFN not being copied.  By requiring that reads be a multiple
of 8 bytes, I can make pm->out and pm->end u64*s instead of char*s, which
makes put_user work properly, and also simplifies the logic in
add_to_pagemap a bit.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Thomas Tuttle <ttuttle@google.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Tuttle 2008-06-05 22:46:31 -07:00 committed by Linus Torvalds
parent d1ee2971f5
commit aae8679b0e
1 changed files with 9 additions and 19 deletions
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28
fs/proc/task_mmu.c
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@ -496,7 +496,7 @@ const struct file_operations proc_clear_refs_operations = {
};
struct pagemapread {
char __user *out, *end;
u64 __user *out, *end;
};
#define PM_ENTRY_BYTES sizeof(u64)
@ -519,21 +519,11 @@ struct pagemapread {
static int add_to_pagemap(unsigned long addr, u64 pfn,
struct pagemapread *pm)
{
/*
* Make sure there's room in the buffer for an
* entire entry. Otherwise, only copy part of
* the pfn.
*/
if (pm->out + PM_ENTRY_BYTES >= pm->end) {
if (copy_to_user(pm->out, &pfn, pm->end - pm->out))
return -EFAULT;
pm->out = pm->end;
return PM_END_OF_BUFFER;
}
if (put_user(pfn, pm->out))
return -EFAULT;
pm->out += PM_ENTRY_BYTES;
pm->out++;
if (pm->out >= pm->end)
return PM_END_OF_BUFFER;
return 0;
}
@ -634,7 +624,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
ret = -EINVAL;
/* file position must be aligned */
if (*ppos % PM_ENTRY_BYTES)
if ((*ppos % PM_ENTRY_BYTES) || (count % PM_ENTRY_BYTES))
goto out_task;
ret = 0;
@ -664,8 +654,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
goto out_pages;
}
pm.out = buf;
pm.end = buf + count;
pm.out = (u64 *)buf;
pm.end = (u64 *)(buf + count);
if (!ptrace_may_attach(task)) {
ret = -EIO;
@ -690,9 +680,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
if (ret == PM_END_OF_BUFFER)
ret = 0;
/* don't need mmap_sem for these, but this looks cleaner */
*ppos += pm.out - buf;
*ppos += (char *)pm.out - buf;
if (!ret)
ret = pm.out - buf;
ret = (char *)pm.out - buf;
}
out_pages: