1 files changed, 96 insertions, 0 deletions

diff --git a/patches/cve/CVE-2017-17852-bpf-fix-32-bit-ALU-op-verification.patch b/patches/cve/CVE-2017-17852-bpf-fix-32-bit-ALU-op-verification.patch
new file mode 100644
index 0000000..000e5cd
--- /dev/null
+++ b/patches/cve/CVE-2017-17852-bpf-fix-32-bit-ALU-op-verification.patch
@@ -0,0 +1,96 @@
+From 6c8e098d0324412d4ae9e06c7e611a96b87faf80 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <daniel@iogearbox.net>
+Date: Fri, 22 Dec 2017 16:23:07 +0100
+Subject: [PATCH] bpf: fix 32-bit ALU op verification
+
+From: Jann Horn <jannh@google.com>
+
+[ Upstream commit 468f6eafa6c44cb2c5d8aad35e12f06c240a812a ]
+
+32-bit ALU ops operate on 32-bit values and have 32-bit outputs.
+Adjust the verifier accordingly.
+
+CVE: CVE-2017-17852
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=6c8e098d0324412d4ae9e06c7e611a96b87faf80]
+
+Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
+Signed-off-by: Jann Horn <jannh@google.com>
+Signed-off-by: Alexei Starovoitov <ast@kernel.org>
+Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
+---
+ kernel/bpf/verifier.c | 28 +++++++++++++++++-----------
+ 1 file changed, 17 insertions(+), 11 deletions(-)
+
+diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
+index 1e2afb264c31..0c7e4c8a2b8a 100644
+--- a/kernel/bpf/verifier.c
++++ b/kernel/bpf/verifier.c
+@@ -1984,6 +1984,10 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
+        return 0;
+ }
+ 
++/* WARNING: This function does calculations on 64-bit values, but the actual
++ * execution may occur on 32-bit values. Therefore, things like bitshifts
++ * need extra checks in the 32-bit case.
++ */
+ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
+                                      struct bpf_insn *insn,
+                                      struct bpf_reg_state *dst_reg,
+@@ -1994,12 +1998,8 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
+        bool src_known, dst_known;
+        s64 smin_val, smax_val;
+        u64 umin_val, umax_val;
++       u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
+ 
+-       if (BPF_CLASS(insn->code) != BPF_ALU64) {
+-               /* 32-bit ALU ops are (32,32)->64 */
+-               coerce_reg_to_size(dst_reg, 4);
+-               coerce_reg_to_size(&src_reg, 4);
+-       }
+        smin_val = src_reg.smin_value;
+        smax_val = src_reg.smax_value;
+        umin_val = src_reg.umin_value;
+@@ -2135,9 +2135,9 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
+                __update_reg_bounds(dst_reg);
+                break;
+        case BPF_LSH:
+-               if (umax_val > 63) {
+-                       /* Shifts greater than 63 are undefined.  This includes
+-                        * shifts by a negative number.
++               if (umax_val >= insn_bitness) {
++                       /* Shifts greater than 31 or 63 are undefined.
++                        * This includes shifts by a negative number.
+                         */
+                        mark_reg_unknown(regs, insn->dst_reg);
+                        break;
+@@ -2163,9 +2163,9 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
+                __update_reg_bounds(dst_reg);
+                break;
+        case BPF_RSH:
+-               if (umax_val > 63) {
+-                       /* Shifts greater than 63 are undefined.  This includes
+-                        * shifts by a negative number.
++               if (umax_val >= insn_bitness) {
++                       /* Shifts greater than 31 or 63 are undefined.
++                        * This includes shifts by a negative number.
+                         */
+                        mark_reg_unknown(regs, insn->dst_reg);
+                        break;
+@@ -2201,6 +2201,12 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
+                break;
+        }
+ 
++       if (BPF_CLASS(insn->code) != BPF_ALU64) {
++               /* 32-bit ALU ops are (32,32)->32 */
++               coerce_reg_to_size(dst_reg, 4);
++               coerce_reg_to_size(&src_reg, 4);
++       }
++
+        __reg_deduce_bounds(dst_reg);
+        __reg_bound_offset(dst_reg);
+        return 0;
+-- 
+2.20.1
+