Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.0 4/7] bpf: fix verifier memory corruption | Date | Sun, 26 Apr 2015 15:40:03 +0200 |
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4.0-stable review patch. If anyone has any objections, please let me know.
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From: Alexei Starovoitov <ast@plumgrid.com>
[ 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@plumgrid.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/bpf/verifier.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1380,7 +1380,8 @@ 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);
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