[3.19.y-ckt stable] Patch "bpf/verifier: reject invalid LD_ABS | BPF_DW instruction" has been added to the 3.19.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    bpf/verifier: reject invalid LD_ABS | BPF_DW instruction

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt20.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From c7a429df465f4b374e241ef2b672ea3cd8eb7fed Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast at fb.com>
Date: Tue, 12 Apr 2016 10:26:19 -0700
Subject: bpf/verifier: reject invalid LD_ABS | BPF_DW instruction

commit d82bccc69041a51f7b7b9b4a36db0772f4cdba21 upstream.

verifier must check for reserved size bits in instruction opcode and
reject BPF_LD | BPF_ABS | BPF_DW and BPF_LD | BPF_IND | BPF_DW instructions,
otherwise interpreter will WARN_RATELIMIT on them during execution.

Fixes: ddd872bc3098 ("bpf: verifier: add checks for BPF_ABS | BPF_IND instructions")
Signed-off-by: Alexei Starovoitov <ast at kernel.org>
Acked-by: Daniel Borkmann <daniel at iogearbox.net>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 kernel/bpf/verifier.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7f68ff6..0d2cbc9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1213,6 +1213,7 @@ static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn)
 	}

 	if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
+	    BPF_SIZE(insn->code) == BPF_DW ||
 	    (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
 		verbose("BPF_LD_ABS uses reserved fields\n");
 		return -EINVAL;
--
2.7.4