linux-kernel - Re: [PATCH] pfn_t: force '~' to be parsed as an unary operator

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <d48b2b1b-201a-d350-6bda-943a66f1abfb@videotron.qc.ca>
Date:   Wed, 24 Oct 2018 19:52:40 -0400
From:   sebhtml <sebhtml@...eotron.qc.ca>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>, acme@...hat.com,
        tz.stoyanov@...il.com, Namhyung Kim <namhyung@...nel.org>,
        zwisler@...nel.org, arangradient@...il.com,
        linux-perf-users@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pfn_t: force '~' to be parsed as an unary operator

On 2018-10-24 6:43 p.m., Andrew Morton wrote:
> 
> I grabbed it, and added cc:stable.
> 
> But aren't we fixing this in the wrong place?  That's a valid
> expression and if this isn't addressed in perf then we may hit a
> similar issue elsewhere...
> 

Right.

Based on:
     git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 01aa9d518eae8a4d75cd3049defc6ed0b6d0a658

In perf, the warning
       [fs_dax:dax_pmd_insert_mapping] unknown op '~'
comes from tools/lib/traceevent/event-parse.c at line 2045:
                 do_warning_event(event, "unknown op '%s'", token);

This is in this function:

static enum tep_event_type
process_op(struct tep_event_format *event, struct tep_print_arg *arg, char **tok);

The code path to reach the good '~' case needs:
         if (arg->type == TEP_PRINT_OP && !arg->op.left) {

I assume that here arg->op.left is not NULL because of (u64) on the left.

~(((u64) ~(~(((1UL) << 12)-1)))
          ^

However, I fail to see where '~' is parsed as a binary operator though.

Any pointer would be welcome.