This is a note to let you know that I've just added the patch titled
fs/xattr.c: zero out memory copied to userspace in getxattr
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-xattr.c-zero-out-memory-copied-to-userspace-in-getxattr.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 81be3dee96346fbe08c31be5ef74f03f6b63cf68 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Mon, 8 May 2017 15:57:24 -0700
Subject: fs/xattr.c: zero out memory copied to userspace in getxattr
From: Michal Hocko <mhocko@xxxxxxxx>
commit 81be3dee96346fbe08c31be5ef74f03f6b63cf68 upstream.
getxattr uses vmalloc to allocate memory if kzalloc fails. This is
filled by vfs_getxattr and then copied to the userspace. vmalloc,
however, doesn't zero out the memory so if the specific implementation
of the xattr handler is sloppy we can theoretically expose a kernel
memory. There is no real sign this is really the case but let's make
sure this will not happen and use vzalloc instead.
Fixes: 779302e67835 ("fs/xattr.c:getxattr(): improve handling of allocation failures")
Link: http://lkml.kernel.org/r/20170306103327.2766-1-mhocko@xxxxxxxxxx
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/xattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -530,7 +530,7 @@ getxattr(struct dentry *d, const char __
size = XATTR_SIZE_MAX;
kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
if (!kvalue) {
- kvalue = vmalloc(size);
+ kvalue = vzalloc(size);
if (!kvalue)
return -ENOMEM;
}
Patches currently in stable-queue which might be from mhocko@xxxxxxxx are
queue-4.9/fs-xattr.c-zero-out-memory-copied-to-userspace-in-getxattr.patch
queue-4.9/mm-prevent-potential-recursive-reclaim-due-to-clearing-pf_memalloc.patch