Commit c3de6317 authored Apr 14, 2015 by Alexei Starovoitov Committed by David S. Miller Apr 16, 2015

bpf: fix verifier memory corruption



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: f1bca824 ("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>

parent f72f116a

kernel/bpf/verifier.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1397,6 +1397,7 @@ peek_stack:
		/* tell verifier to check for equivalent states
		* after every call and jump
		*/
		if (t + 1 < insn_cnt)
		env->explored_states[t + 1] = STATE_LIST_MARK;
		} else {
		/* conditional jump with two edges */

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