From: akpm@linux-foundation.org
To: william.kucharski@oracle.com, tsoni@codeaurora.org,
stable@vger.kernel.org, psodagud@codeaurora.org,
keescook@chromium.org, gregkh@linuxfoundation.org,
isaacm@codeaurora.org, akpm@linux-foundation.org,
mm-commits@vger.kernel.org, torvalds@linux-foundation.org
Subject: [patch 11/18] mm/usercopy: use memory range to be accessed for wraparound check
Date: Tue, 13 Aug 2019 15:37:37 -0700 [thread overview]
Message-ID: <20190813223737.DHDZP%akpm@linux-foundation.org> (raw)
From: "Isaac J. Manjarres" <isaacm@codeaurora.org>
Subject: mm/usercopy: use memory range to be accessed for wraparound check
Currently, when checking to see if accessing n bytes starting at address
"ptr" will cause a wraparound in the memory addresses, the check in
check_bogus_address() adds an extra byte, which is incorrect, as the range
of addresses that will be accessed is [ptr, ptr + (n - 1)].
This can lead to incorrectly detecting a wraparound in the memory address,
when trying to read 4 KB from memory that is mapped to the the last
possible page in the virtual address space, when in fact, accessing that
range of memory would not cause a wraparound to occur.
Use the memory range that will actually be accessed when considering if
accessing a certain amount of bytes will cause the memory address to wrap
around.
Link: http://lkml.kernel.org/r/1564509253-23287-1-git-send-email-isaacm@codeaurora.org
Fixes: f5509cc18daa ("mm: Hardened usercopy")
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Co-developed-by: Prasad Sodagudi <psodagud@codeaurora.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Trilok Soni <tsoni@codeaurora.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/usercopy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/usercopy.c~mm-usercopy-use-memory-range-to-be-accessed-for-wraparound-check
+++ a/mm/usercopy.c
@@ -147,7 +147,7 @@ static inline void check_bogus_address(c
bool to_user)
{
/* Reject if object wraps past end of memory. */
- if (ptr + n < ptr)
+ if (ptr + (n - 1) < ptr)
usercopy_abort("wrapped address", NULL, to_user, 0, ptr + n);
/* Reject if NULL or ZERO-allocation. */
_
reply other threads:[~2019-08-13 22:37 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20190813223737.DHDZP%akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=isaacm@codeaurora.org \
--cc=keescook@chromium.org \
--cc=mm-commits@vger.kernel.org \
--cc=psodagud@codeaurora.org \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=tsoni@codeaurora.org \
--cc=william.kucharski@oracle.com \
/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).