diff options
| author | Jiri Olsa <jolsa@kernel.org> | 2016-09-08 10:57:08 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-09-20 23:32:49 +0300 |
| commit | df04abfd181acc276ba6762c8206891ae10ae00d (patch) | |
| tree | 03afe92ae5ef3e51035ab871e0b29742d11eb0d1 | |
| parent | f5beeb1851ea6f8cfcf2657f26cb24c0582b4945 (diff) | |
| download | linux-df04abfd181acc276ba6762c8206891ae10ae00d.tar.xz | |
fs/proc/kcore.c: Add bounce buffer for ktext data
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: f5509cc18daa ("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>
| -rw-r--r-- | fs/proc/kcore.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index bd3ac9dca252..5c89a07e3d7f 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -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 |