Re: ebpf: BPF_ALU32 | BPF_ARSH on BE arches

[Yauheni Kaliuta]

Hi, Jiong!

>>>>> On Tue, 25 Jun 2019 11:20:07 +0100, Jiong Wang  wrote:

 > Yauheni Kaliuta writes:

 >> Hi!
 >> 
 >> Looks like the code:
 >> 
 >> ALU_ARSH_X:
 >> DST = (u64) (u32) ((*(s32 *) &DST) >> SRC);
 >> CONT;
 >> ALU_ARSH_K:
 >> DST = (u64) (u32) ((*(s32 *) &DST) >> IMM);
 >> CONT;
 >> 
 >> works incorrectly on BE arches since it must operate on lower
 >> parts of 64bit registers.
 >> 
 >> See failure of test_verifier test 'arsh32 on imm 2' (#23 on
 >> 5.2-rc6).

 > Ah, thanks for reporting this.

 > Should not taken the address directly, does the following fix resolved the
 > failure?

 >         ALU_ARSH_X:
 >                 DST = (u64) (u32) ((s32) DST) >> SRC);
 >                 CONT;
 >         ALU_ARSH_K:
 >                 DST = (u64) (u32) ((s32) DST) >> IMM);
 >                 CONT;

Yes, thanks (just add the missing braces).

-- 
WBR,
Yauheni Kaliuta