On 08/23/2017 04:09 PM, Edward Cree wrote:
Writes in straight-line code should not prevent reads from propagating
along jumps. With current verifier code, the jump from 3 to 5 does not
add a read mark on 3:R0 (because 5:R0 has a write mark), meaning that
the jump from 1 to 3 gets pruned as safe even though R0 is NOT_INIT.
Verifier output:
0: (61) r2 = *(u32 *)(r1 +0)
1: (35) if r2 >= 0x0 goto pc+1
R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umax_value=4294967295,var_off=(0x0;
0xffffffff)) R10=fp0
2: (b7) r0 = 0
3: (35) if r2 >= 0x0 goto pc+1
R0=inv0 R1=ctx(id=0,off=0,imm=0)
R2=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
4: (b7) r0 = 0
5: (95) exit
from 3 to 5: safe
from 1 to 3: safe
processed 8 insns, stack depth 0
Signed-off-by: Edward Cree <ec...@solarflare.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
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