lkml.org 
[lkml]   [2012]   [Oct]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[ 028/180] oprofile: use KM_NMI slot for kmap_atomic
2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Junxiao Bi <junxiao.bi@oracle.com>

If one kernel path is using KM_USER0 slot and is interrupted by
the oprofile nmi, then in copy_from_user_nmi(), the KM_USER0 slot
will be overwrite and cleared to zero at last, when the control
return to the original kernel path, it will access an invalid
virtual address and trigger a crash.

Cc: Robert Richter <robert.richter@amd.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>

[WT: According to Junxiao and Robert, this patch is needed for stable kernels
which include a backport of a0e3e70243f5b270bc3eca718f0a9fa5e6b8262e without
3e4d3af501cccdc8a8cca41bdbe57d54ad7e7e73, but there is no exact equivalent in
mainline]
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/x86/oprofile/backtrace.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 829edf0..b50a280 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -71,9 +71,9 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
offset = addr & (PAGE_SIZE - 1);
size = min(PAGE_SIZE - offset, n - len);

- map = kmap_atomic(page, KM_USER0);
+ map = kmap_atomic(page, KM_NMI);
memcpy(to, map+offset, size);
- kunmap_atomic(map, KM_USER0);
+ kunmap_atomic(map, KM_NMI);
put_page(page);

len += size;
--
1.7.2.1.45.g54fbc




\
 
 \ /
  Last update: 2012-10-02 01:41    [W:1.434 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site