summaryrefslogtreecommitdiffstats
path: root/kernel/bpf
diff options
context:
space:
mode:
authorAndrey Ignatov <rdna@fb.com>2019-04-03 23:22:37 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2019-04-05 16:50:07 +0200
commitf2bcd05ec7b839ff826d2008506ad2d2dff46a59 (patch)
treedcd402f6de719741c4e554a45ec7610d6971b1e9 /kernel/bpf
parent636e78b1cdb40b77a79b143dbd9d94847b360efa (diff)
downloadlinux-f2bcd05ec7b839ff826d2008506ad2d2dff46a59.tar.bz2
bpf: Reject indirect var_off stack access in raw mode
It's hard to guarantee that whole memory is marked as initialized on helper return if uninitialized stack is accessed with variable offset since specific bounds are unknown to verifier. This may cause uninitialized stack leaking. Reject such an access in check_stack_boundary to prevent possible leaking. There are no known use-cases for indirect uninitialized stack access with variable offset so it shouldn't break anything. Fixes: 2011fccfb61b ("bpf: Support variable offset stack access from helpers") Reported-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bb27b675923c..0f12fda35626 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2226,6 +2226,15 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
if (err)
return err;
} else {
+ /* Only initialized buffer on stack is allowed to be accessed
+ * with variable offset. With uninitialized buffer it's hard to
+ * guarantee that whole memory is marked as initialized on
+ * helper return since specific bounds are unknown what may
+ * cause uninitialized stack leaking.
+ */
+ if (meta && meta->raw_mode)
+ meta = NULL;
+
min_off = reg->smin_value + reg->off;
max_off = reg->umax_value + reg->off;
err = __check_stack_boundary(env, regno, min_off, access_size,