From: Michal Hocko Date: Mon, 8 May 2017 22:57:24 +0000 (-0700) Subject: fs/xattr.c: zero out memory copied to userspace in getxattr X-Git-Tag: release-20171130_firefly~4^2~100^2~1^2~8^2~23 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=eb04a7344c83fdbed0a910d7e1dd31f82606d6ec;p=firefly-linux-kernel-4.4.55.git fs/xattr.c: zero out memory copied to userspace in getxattr 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@kernel.org Acked-by: Kees Cook Reported-by: Vlastimil Babka Signed-off-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/xattr.c b/fs/xattr.c index 9b932b95d74e..f0da9d24e9ca 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -442,7 +442,7 @@ getxattr(struct dentry *d, const char __user *name, void __user *value, size = XATTR_SIZE_MAX; kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); if (!kvalue) { - vvalue = vmalloc(size); + vvalue = vzalloc(size); if (!vvalue) return -ENOMEM; kvalue = vvalue;