From: Alexei Starovoitov <ast@xxxxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit c3de6317d748e23b9e46ba36e10483728d00d144 ]
Due to missing bounds check the DAG pass of the BPF verifier can corrupt
the memory which can cause random crashes during program loading:
[8.449451] BUG: unable to handle kernel paging request at ffffffffffffffff
[8.451293] IP: [<ffffffff811de33d>] kmem_cache_alloc_trace+0x8d/0x2f0
[8.452329] Oops: 0000 [#1] SMP
[8.452329] Call Trace:
[8.452329] [<ffffffff8116cc82>] bpf_check+0x852/0x2000
[8.452329] [<ffffffff8116b7e4>] bpf_prog_load+0x1e4/0x310
[8.452329] [<ffffffff811b190f>] ? might_fault+0x5f/0xb0
[8.452329] [<ffffffff8116c206>] SyS_bpf+0x806/0xa30
Fixes: f1bca824dabb ("bpf: add search pruning optimization to verifier")
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
kernel/bpf/verifier.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9f81818..d8dcc80 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1324,7 +1324,8 @@ peek_stack:
/* tell verifier to check for equivalent states
* after every call and jump
*/
- env->explored_states[t + 1] = STATE_LIST_MARK;
+ if (t + 1 < insn_cnt)
+ env->explored_states[t + 1] = STATE_LIST_MARK;
} else {
/* conditional jump with two edges */
ret = push_insn(t, t + 1, FALLTHROUGH, env);
--
2.1.0
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