linux-kernel - Re: [PATCH v2 02/24] objtool: Introduce CFI hash

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LSU.2.21.2106301431120.32505@pobox.suse.cz>
Date:   Wed, 30 Jun 2021 14:45:57 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Peter Zijlstra <peterz@...radead.org>
cc:     jpoimboe@...hat.com, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, joro@...tes.org,
        boris.ostrovsky@...cle.com, jgross@...e.com, x86@...nel.org,
        mbenes@...e.com, rostedt@...dmis.org, dvyukov@...gle.com,
        elver@...gle.com, Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH v2 02/24] objtool: Introduce CFI hash

> @@ -2725,15 +2820,24 @@ static int validate_branch(struct objtoo
>  
>  			if (insn->visited & visited)
>  				return 0;
> -		}
> +		} else
> +			nr_visited++;

just a coding style

	} else {
		nr_visited++;
	}

> @@ -3192,6 +3304,13 @@ int check(struct objtool_file *file)
>  		warnings += ret;
>  	}
>  
> +	if (stats) {
> +		printf("nr_visited: %ld\n", nr_visited);

Could we make this nr_insns_visited?

> +		printf("nr_cfi: %ld\n", nr_cfi);
> +		printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
> +		printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
> +	}
> +
> +++ b/tools/objtool/orc_gen.c
> @@ -13,13 +13,19 @@
>  #include <objtool/warn.h>
>  #include <objtool/endianness.h>
>  
> -static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
> +static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
> +			  struct instruction *insn)
>  {
> -	struct instruction *insn = container_of(cfi, struct instruction, cfi);
>  	struct cfi_reg *bp = &cfi->regs[CFI_BP];
>  
>  	memset(orc, 0, sizeof(*orc));
>  
> +	if (!cfi) {
> +		orc->end = 0;
> +		orc->sp_reg = ORC_REG_UNDEFINED;
> +		return 0;
> +	}
> +

This looks strange. You access cfi a couple of lines earlier (bp cfi_reg 
initialization).

Is it even possible to have cfi == NULL here? The second call site below 
has a check and the first one should not happen (insn->cfip should be 
always set if I am not missing something).

>  	orc->end = cfi->end;
>  
>  	if (cfi->cfa.base == CFI_UNDEFINED) {
> @@ -162,7 +168,7 @@ int orc_create(struct objtool_file *file
>  			int i;
>  
>  			if (!alt_group) {
> -				if (init_orc_entry(&orc, &insn->cfi))
> +				if (init_orc_entry(&orc, insn->cfip, insn))
>  					return -1;
>  				if (!memcmp(&prev_orc, &orc, sizeof(orc)))
>  					continue;
> @@ -186,7 +192,8 @@ int orc_create(struct objtool_file *file
>  				struct cfi_state *cfi = alt_group->cfi[i];
>  				if (!cfi)
>  					continue;
> -				if (init_orc_entry(&orc, cfi))
> +				/* errors are reported on the original insn */
> +				if (init_orc_entry(&orc, cfi, insn))
>  					return -1;
>  				if (!memcmp(&prev_orc, &orc, sizeof(orc)))
>  					continue;

Anyway, this is a nice improvement.

Miroslav