4.1-stable review patch. If anyone has any objections, please let me know.
------------------ From: Michael Holzheu <[email protected]> commit b035b60ded132592055c0f9bd1cc280259c7de4b upstream. Currently all backward jumps crash for JITed s390x eBPF programs with an illegal instruction program check and kernel panic. Because for negative values the opcode of the jump instruction is overriden by the negative branch offset an illegal instruction is generated by the JIT: 000003ff802da378: c01100000002 lgfi %r1,2 000003ff802da37e: fffffff52065 unknown <-- illegal instruction 000003ff802da384: b904002e lgr %r2,%r14 So fix this and mask the offset in order not to damage the opcode. Signed-off-by: Michael Holzheu <[email protected]> Signed-off-by: Martin Schwidefsky <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/s390/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -227,7 +227,7 @@ static inline void reg_set_seen(struct b ({ \ /* Branch instruction needs 6 bytes */ \ int rel = (addrs[i + off + 1] - (addrs[i + 1] - 6)) / 2;\ - _EMIT6(op1 | reg(b1, b2) << 16 | rel, op2 | mask); \ + _EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff), op2 | mask); \ REG_SET_SEEN(b1); \ REG_SET_SEEN(b2); \ }) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
