This is a note to let you know that I've just added the patch titled
bpf/verifier: fix min/max handling in BPF_SUB
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-verifier-fix-min-max-handling-in-bpf_sub.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Aug 24 17:44:02 PDT 2017
From: Edward Cree <ecree@xxxxxxxxxxxxxx>
Date: Fri, 21 Jul 2017 14:37:34 +0100
Subject: bpf/verifier: fix min/max handling in BPF_SUB
From: Edward Cree <ecree@xxxxxxxxxxxxxx>
[ Upstream commit 9305706c2e808ae59f1eb201867f82f1ddf6d7a6 ]
We have to subtract the src max from the dst min, and vice-versa, since
(e.g.) the smallest result comes from the largest subtrahend.
Fixes: 484611357c19 ("bpf: allow access into map value arrays")
Signed-off-by: Edward Cree <ecree@xxxxxxxxxxxxxx>
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/bpf/verifier.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1624,10 +1624,12 @@ static void adjust_reg_min_max_vals(stru
* do our normal operations to the register, we need to set the values
* to the min/max since they are undefined.
*/
- if (min_val == BPF_REGISTER_MIN_RANGE)
- dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
- if (max_val == BPF_REGISTER_MAX_RANGE)
- dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
+ if (opcode != BPF_SUB) {
+ if (min_val == BPF_REGISTER_MIN_RANGE)
+ dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
+ if (max_val == BPF_REGISTER_MAX_RANGE)
+ dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
+ }
switch (opcode) {
case BPF_ADD:
@@ -1637,10 +1639,17 @@ static void adjust_reg_min_max_vals(stru
dst_reg->max_value += max_val;
break;
case BPF_SUB:
+ /* If one of our values was at the end of our ranges, then the
+ * _opposite_ value in the dst_reg goes to the end of our range.
+ */
+ if (min_val == BPF_REGISTER_MIN_RANGE)
+ dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
+ if (max_val == BPF_REGISTER_MAX_RANGE)
+ dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
- dst_reg->min_value -= min_val;
+ dst_reg->min_value -= max_val;
if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
- dst_reg->max_value -= max_val;
+ dst_reg->max_value -= min_val;
break;
case BPF_MUL:
if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
Patches currently in stable-queue which might be from ecree@xxxxxxxxxxxxxx are
queue-4.9/bpf-fix-mixed-signed-unsigned-derived-min-max-value-bounds.patch
queue-4.9/bpf-verifier-fix-min-max-handling-in-bpf_sub.patch