Cfg jset fix #9116
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Cfg jset fix #9116
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BPF_JSET is a conditional jump and currently verifier.c:can_jump() does not know about that. This can lead to incorrect live registers and SCC computation. E.g. in the following example: 1: r0 = 1; 2: r2 = 2; 3: if r1 & 0x7 goto +1; 4: exit; 5: r0 = r2; 6: exit; W/o this fix insn_successors(3) will return only (4), a jump to (5) would be missed and r2 won't be marked as alive at (3). Fixes: 14c8552 ("bpf: simple DFA-based live registers analysis") Reported-by: [email protected] Suggested-by: Alexei Starovoitov <[email protected]> Signed-off-by: Eduard Zingerman <[email protected]>
A test case to check if both branches of jset are explored when computing program CFG. At 'if r1 & 0x7 ...': - register 'r2' is computed alive only if jump branch of jset instruction is followed; - register 'r0' is computed alive only if fallthrough branch of jset instruction is followed. Signed-off-by: Eduard Zingerman <[email protected]>
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