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>
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 88717c0..1740362 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -496,7 +496,7 @@
};
struct pagemapread {
- char __user *out, *end;
+ u64 __user *out, *end;
};
#define PM_ENTRY_BYTES sizeof(u64)
@@ -519,21 +519,11 @@
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 @@
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 @@
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 @@
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: