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: v3.18.54~32 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cea7e7245ea80f96031cb128a2a6d409bbd6535e;p=linux 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 64e83efb742d..2ac964e32daf 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -444,7 +444,7 @@ 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;