renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-17 09:43:59 +08:00
Code

fs/proc/kcore.c: Add bounce buffer for ktext data

Browse Source 
We hit hardened usercopy feature check for kernel text access by reading
kcore file:

  usercopy: kernel memory exposure attempt detected from ffffffff8179a01f (<kernel text>) (4065 bytes)
  kernel BUG at mm/usercopy.c:75!

Bypassing this check for kcore by adding bounce buffer for ktext data.

Reported-by: Steve Best <sbest@redhat.com>
Fixes: f5509cc18d ("mm: Hardened usercopy")
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jiri Olsa 2016-09-08 09:57:08 +02:00 committed by Linus Torvalds
parent f5beeb1851
commit df04abfd18
1 changed files with 6 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
fs/proc/kcore.c
View File

@ -509,7 +509,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
if (kern_addr_valid(start)) {
unsigned long n;
n = copy_to_user(buffer, (char *)start, tsz);
/*
* Using bounce buffer to bypass the
* hardened user copy kernel text checks.
*/
memcpy(buf, (char *) start, tsz);
n = copy_to_user(buffer, buf, tsz);
/*
* We cannot distinguish between fault on source
* and fault on destination. When this happens