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Merge branch 'bpf-fixes'

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Daniel Borkmann says:

====================
Two BPF fixes

The set fixes cb_access and xdp_adjust_head bits in struct bpf_prog,
that are used for requirement checks on the program rather than f.e.
heuristics. Thus, for tail calls, we cannot make any assumptions and
are forced to set them.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2017-04-17 15:51:58 -04:00
commit acf167f3f2
1 changed files with 8 additions and 0 deletions
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8
kernel/bpf/syscall.c
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@ -617,6 +617,14 @@ static void fixup_bpf_calls(struct bpf_prog *prog)
if (insn->imm == BPF_FUNC_xdp_adjust_head)
prog->xdp_adjust_head = 1;
if (insn->imm == BPF_FUNC_tail_call) {
/* If we tail call into other programs, we
* cannot make any assumptions since they
* can be replaced dynamically during runtime
* in the program array.
*/
prog->cb_access = 1;
prog->xdp_adjust_head = 1;
/* mark bpf_tail_call as different opcode
* to avoid conditional branch in
* interpeter for every normal call