4.9-stable patches

added patches:
	bpf-fix-passing-modified-ctx-to-ld-abs-ind-instruction.patch

diff --git a/queue-4.9/bpf-fix-passing-modified-ctx-to-ld-abs-ind-instruction.patch b/queue-4.9/bpf-fix-passing-modified-ctx-to-ld-abs-ind-instruction.patch
new file mode 100644 (file)
index 0000000..de409d1
--- /dev/null
+++ b/queue-4.9/bpf-fix-passing-modified-ctx-to-ld-abs-ind-instruction.patch
@@ -0,0 +1,117 @@
+From 6d4f151acf9a4f6fab09b615f246c717ddedcf0c Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <daniel@iogearbox.net>
+Date: Mon, 6 Jan 2020 22:51:57 +0100
+Subject: bpf: Fix passing modified ctx to ld/abs/ind instruction
+
+From: Daniel Borkmann <daniel@iogearbox.net>
+
+commit 6d4f151acf9a4f6fab09b615f246c717ddedcf0c upstream.
+
+Anatoly has been fuzzing with kBdysch harness and reported a KASAN
+slab oob in one of the outcomes:
+
+  [...]
+  [   77.359642] BUG: KASAN: slab-out-of-bounds in bpf_skb_load_helper_8_no_cache+0x71/0x130
+  [   77.360463] Read of size 4 at addr ffff8880679bac68 by task bpf/406
+  [   77.361119]
+  [   77.361289] CPU: 2 PID: 406 Comm: bpf Not tainted 5.5.0-rc2-xfstests-00157-g2187f215eba #1
+  [   77.362134] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
+  [   77.362984] Call Trace:
+  [   77.363249]  dump_stack+0x97/0xe0
+  [   77.363603]  print_address_description.constprop.0+0x1d/0x220
+  [   77.364251]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
+  [   77.365030]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
+  [   77.365860]  __kasan_report.cold+0x37/0x7b
+  [   77.366365]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
+  [   77.366940]  kasan_report+0xe/0x20
+  [   77.367295]  bpf_skb_load_helper_8_no_cache+0x71/0x130
+  [   77.367821]  ? bpf_skb_load_helper_8+0xf0/0xf0
+  [   77.368278]  ? mark_lock+0xa3/0x9b0
+  [   77.368641]  ? kvm_sched_clock_read+0x14/0x30
+  [   77.369096]  ? sched_clock+0x5/0x10
+  [   77.369460]  ? sched_clock_cpu+0x18/0x110
+  [   77.369876]  ? bpf_skb_load_helper_8+0xf0/0xf0
+  [   77.370330]  ___bpf_prog_run+0x16c0/0x28f0
+  [   77.370755]  __bpf_prog_run32+0x83/0xc0
+  [   77.371153]  ? __bpf_prog_run64+0xc0/0xc0
+  [   77.371568]  ? match_held_lock+0x1b/0x230
+  [   77.371984]  ? rcu_read_lock_held+0xa1/0xb0
+  [   77.372416]  ? rcu_is_watching+0x34/0x50
+  [   77.372826]  sk_filter_trim_cap+0x17c/0x4d0
+  [   77.373259]  ? sock_kzfree_s+0x40/0x40
+  [   77.373648]  ? __get_filter+0x150/0x150
+  [   77.374059]  ? skb_copy_datagram_from_iter+0x80/0x280
+  [   77.374581]  ? do_raw_spin_unlock+0xa5/0x140
+  [   77.375025]  unix_dgram_sendmsg+0x33a/0xa70
+  [   77.375459]  ? do_raw_spin_lock+0x1d0/0x1d0
+  [   77.375893]  ? unix_peer_get+0xa0/0xa0
+  [   77.376287]  ? __fget_light+0xa4/0xf0
+  [   77.376670]  __sys_sendto+0x265/0x280
+  [   77.377056]  ? __ia32_sys_getpeername+0x50/0x50
+  [   77.377523]  ? lock_downgrade+0x350/0x350
+  [   77.377940]  ? __sys_setsockopt+0x2a6/0x2c0
+  [   77.378374]  ? sock_read_iter+0x240/0x240
+  [   77.378789]  ? __sys_socketpair+0x22a/0x300
+  [   77.379221]  ? __ia32_sys_socket+0x50/0x50
+  [   77.379649]  ? mark_held_locks+0x1d/0x90
+  [   77.380059]  ? trace_hardirqs_on_thunk+0x1a/0x1c
+  [   77.380536]  __x64_sys_sendto+0x74/0x90
+  [   77.380938]  do_syscall_64+0x68/0x2a0
+  [   77.381324]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
+  [   77.381878] RIP: 0033:0x44c070
+  [...]
+
+After further debugging, turns out while in case of other helper functions
+we disallow passing modified ctx, the special case of ld/abs/ind instruction
+which has similar semantics (except r6 being the ctx argument) is missing
+such check. Modified ctx is impossible here as bpf_skb_load_helper_8_no_cache()
+and others are expecting skb fields in original position, hence, add
+check_ctx_reg() to reject any modified ctx. Issue was first introduced back
+in f1174f77b50c ("bpf/verifier: rework value tracking").
+
+Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
+Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
+Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
+Signed-off-by: Alexei Starovoitov <ast@kernel.org>
+Link: https://lore.kernel.org/bpf/20200106215157.3553-1-daniel@iogearbox.net
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/bpf/verifier.c |    9 +++++++--
+ 1 file changed, 7 insertions(+), 2 deletions(-)
+
+--- a/kernel/bpf/verifier.c
++++ b/kernel/bpf/verifier.c
+@@ -2422,6 +2422,7 @@ static bool may_access_skb(enum bpf_prog
+ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
+ {
+       struct bpf_reg_state *regs = env->cur_state.regs;
++      static const int ctx_reg = BPF_REG_6;
+       u8 mode = BPF_MODE(insn->code);
+       struct bpf_reg_state *reg;
+       int i, err;
+@@ -2439,11 +2440,11 @@ static int check_ld_abs(struct bpf_verif
+       }
+ 
+       /* check whether implicit source operand (register R6) is readable */
+-      err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
++      err = check_reg_arg(regs, ctx_reg, SRC_OP);
+       if (err)
+               return err;
+ 
+-      if (regs[BPF_REG_6].type != PTR_TO_CTX) {
++      if (regs[ctx_reg].type != PTR_TO_CTX) {
+               verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
+               return -EINVAL;
+       }
+@@ -2455,6 +2456,10 @@ static int check_ld_abs(struct bpf_verif
+                       return err;
+       }
+ 
++      err = check_ctx_reg(env, &regs[ctx_reg], ctx_reg);
++      if (err < 0)
++              return err;
++
+       /* reset caller saved regs to unreadable */
+       for (i = 0; i < CALLER_SAVED_REGS; i++) {
+               reg = regs + caller_saved[i];

diff --git a/queue-4.9/series b/queue-4.9/series
index d8bc8e6320acf2e48130fa7a1e9edc89dea3e519..ecdca3f3ea25884600bd576bed4ee1ee751b1fa8 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -54,3 +54,4 @@ s390-smp-fix-physical-to-logical-cpu-map-for-smt.patch
 xen-blkback-avoid-unmapping-unmapped-grant-pages.patch
 locking-x86-remove-the-unused-atomic_inc_short-methd.patch
 pstore-ram-write-new-dumps-to-start-of-recycled-zone.patch
+bpf-fix-passing-modified-ctx-to-ld-abs-ind-instruction.patch