From: David Hildenbrand <david@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
Kees Cook <keescook@chromium.org>
Cc: linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 3/4] mm/usercopy: Detect large folio overruns
Date: Mon, 31 Jan 2022 15:28:36 +0100 [thread overview]
Message-ID: <f36cdc92-c52a-664e-dad9-fccfa5c187d5@redhat.com> (raw)
In-Reply-To: <20220110231530.665970-4-willy@infradead.org>
On 11.01.22 00:15, Matthew Wilcox (Oracle) wrote:
> Move the compound page overrun detection out of
> CONFIG_HARDENED_USERCOPY_PAGESPAN and convert it to use folios so it's
> enabled for more people.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Acked-by: Kees Cook <keescook@chromium.org>
> ---
> mm/usercopy.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index dcf71b7e3098..e1cb98087a05 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -164,7 +164,6 @@ static inline void check_page_span(const void *ptr, unsigned long n,
> {
> #ifdef CONFIG_HARDENED_USERCOPY_PAGESPAN
> const void *end = ptr + n - 1;
> - struct page *endpage;
> bool is_reserved, is_cma;
>
> /*
> @@ -195,11 +194,6 @@ static inline void check_page_span(const void *ptr, unsigned long n,
> ((unsigned long)end & (unsigned long)PAGE_MASK)))
> return;
>
> - /* Allow if fully inside the same compound (__GFP_COMP) page. */
> - endpage = virt_to_head_page(end);
> - if (likely(endpage == page))
> - return;
> -
> /*
> * Reject if range is entirely either Reserved (i.e. special or
> * device memory), or CMA. Otherwise, reject since the object spans
> @@ -259,6 +253,10 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
> if (folio_test_slab(folio)) {
> /* Check slab allocator for flags and size. */
> __check_heap_object(ptr, n, folio_slab(folio), to_user);
> + } else if (folio_test_large(folio)) {
> + unsigned long offset = ptr - folio_address(folio);
Nit: I'd have added an empty line.
> + if (offset + n > folio_size(folio))
> + usercopy_abort("page alloc", NULL, to_user, offset, n);
> } else {
> /* Verify object does not incorrectly span multiple pages. */
> check_page_span(ptr, n, folio_page(folio, 0), to_user);
LGTM
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2022-01-31 14:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-10 23:15 [PATCH 0/4] Assorted improvements to usercopy Matthew Wilcox (Oracle)
2022-01-10 23:15 ` [PATCH 1/4] mm/usercopy: Check kmap addresses properly Matthew Wilcox (Oracle)
2022-05-10 3:37 ` Andrew Morton
2022-05-10 22:01 ` Kees Cook
2022-01-10 23:15 ` [PATCH 2/4] mm/usercopy: Detect vmalloc overruns Matthew Wilcox (Oracle)
2022-01-10 23:15 ` [PATCH 3/4] mm/usercopy: Detect large folio overruns Matthew Wilcox (Oracle)
2022-01-31 14:28 ` David Hildenbrand [this message]
2022-01-10 23:15 ` [PATCH 4/4] usercopy: Remove HARDENED_USERCOPY_PAGESPAN Matthew Wilcox (Oracle)
2022-01-12 23:08 ` Kees Cook
2022-01-31 14:27 ` David Hildenbrand
2022-01-31 19:27 ` Matthew Wilcox
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f36cdc92-c52a-664e-dad9-fccfa5c187d5@redhat.com \
--to=david@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).