netdev - Re: [PATCH v3 bpf-next 1/5] mm/error_inject: Fix allow_error

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

Date:   Thu, 27 Aug 2020 19:58:57 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        davem@...emloft.net
Cc:     daniel@...earbox.net, bpoirier@...e.com, akpm@...ux-foundation.org,
        hannes@...xchg.org, netdev@...r.kernel.org, bpf@...r.kernel.org,
        kernel-team@...com
Subject: Re: [PATCH v3 bpf-next 1/5] mm/error_inject: Fix allow_error_inject
 function signatures.

On 8/27/20 6:01 PM, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@...nel.org>
> 
> 'static' and 'static noinline' function attributes make no guarantees that
> gcc/clang won't optimize them. The compiler may decide to inline 'static'
> function and in such case ALLOW_ERROR_INJECT becomes meaningless. The compiler
> could have inlined __add_to_page_cache_locked() in one callsite and didn't
> inline in another. In such case injecting errors into it would cause
> unpredictable behavior. It's worse with 'static noinline' which won't be
> inlined, but it still can be optimized. Like the compiler may decide to remove
> one argument or constant propagate the value depending on the callsite.
> 
> To avoid such issues make sure that these functions are global noinline.
> 
> Fixes: af3b854492f3 ("mm/page_alloc.c: allow error injection")
> Fixes: cfcbfb1382db ("mm/filemap.c: enable error injection at add_to_page_cache()")
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Reviewed-by: Josef Bacik <josef@...icpanda.com>

Thanks,

Josef