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  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:   Tue, 18 Jan 2022 20:32:43 +0100
From:   Jann Horn <>
To:     Kees Cook <>
Cc:     Peter Huewe <>,
        Jarkko Sakkinen <>,
        Jason Gunthorpe <>,,
        Stefan Berger <>,,
Subject: Re: [PATCH v2] tpm: vtpm_proxy: Double-check to avoid buffer overflow

On Tue, Jan 18, 2022 at 7:37 PM Kees Cook <> wrote:
> When building with -Warray-bounds, this warning was emitted:
> In function 'memset',
>     inlined from 'vtpm_proxy_fops_read' at drivers/char/tpm/tpm_vtpm_proxy.c:102:2:
> ./include/linux/fortify-string.h:43:33: warning: '__builtin_memset' pointer overflow between offset 164 and size [2147483648, 4294967295]
> [-Warray-bounds]
>    43 | #define __underlying_memset     __builtin_memset
>       |                                 ^

Can you explain what that compiler warning actually means, and which
compiler it is from? Is this from a 32-bit or a 64-bit architecture?

It sounds like the compiler (GCC?) is hallucinating a codepath on
which "len" is guaranteed to be >=2147483648, right? Why is it doing
that? Is this some kinda side effect from the fortify code?

Powered by blists - more mailing lists