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Date: Thu, 18 May 2017 15:16:27 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Kees Cook <keescook@...omium.org>, Vlastimil Babka <vbabka@...e.cz>, Michal Hocko <mhocko@...e.com>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: [PATCH 3.18 18/49] fs/xattr.c: zero out memory copied to userspace in getxattr 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michal Hocko <mhocko@...e.com> 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 <keescook@...omium.org> Reported-by: Vlastimil Babka <vbabka@...e.cz> Signed-off-by: Michal Hocko <mhocko@...e.com> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/xattr.c +++ b/fs/xattr.c @@ -444,7 +444,7 @@ getxattr(struct dentry *d, const char __ 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;
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