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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Kees Cook <keescook@chromium.org>, linux-hardening@vger.kernel.org
Cc: Juergen Gross <jgross@suse.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	xen-devel@lists.xenproject.org, llvm@lists.linux.dev,
	Siddhesh Poyarekar <siddhesh@gotplt.org>,
	Arnd Bergmann <arnd@arndb.de>, Tom Rix <trix@redhat.com>,
	Miguel Ojeda <ojeda@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] x86/entry: Work around Clang __bdos() bug
Date: Tue, 20 Sep 2022 20:07:09 -0400	[thread overview]
Message-ID: <41527d69-e8ab-3f86-ff37-6b298c01d5bc@oracle.com> (raw)
In-Reply-To: <20220920192202.190793-2-keescook@chromium.org>


On 9/20/22 3:21 PM, Kees Cook wrote:
> After expanding bounds checking to use __builtin_dynamic_object_size(),
> Clang produces a false positive when building with CONFIG_FORTIFY_SOURCE=y
> and CONFIG_UBSAN_BOUNDS=y when operating on an array with a dynamic
> offset. Work around this by using a direct assignment of an empty
> instance. Avoids this warning:
>
> ../include/linux/fortify-string.h:309:4: warning: call to __write_overflow_field declared with 'warn
> ing' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wat
> tribute-warning]
>                          __write_overflow_field(p_size_field, size);
>                          ^
>
> which was isolated to the memset() call in xen_load_idt().
>
> Note that this looks very much like another bug that was worked around:
> https://github.com/ClangBuiltLinux/linux/issues/1592
>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: xen-devel@lists.xenproject.org
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>



  reply	other threads:[~2022-09-21  0:07 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20 19:21 [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-20 19:21 ` [PATCH 1/4] x86/entry: Work around Clang __bdos() bug Kees Cook
2022-09-21  0:07   ` Boris Ostrovsky [this message]
2022-09-20 19:22 ` [PATCH 2/4] fortify: Explicitly check bounds are compile-time constants Kees Cook
2022-09-21 11:48   ` Siddhesh Poyarekar
2022-09-22  3:46     ` Kees Cook
2022-09-20 19:22 ` [PATCH 3/4] fortify: Convert to struct vs member helpers Kees Cook
2022-09-20 19:22 ` [PATCH 4/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-21 11:24   ` Miguel Ojeda
2022-09-21 11:43   ` Siddhesh Poyarekar
2022-09-22  3:33     ` Kees Cook
2022-09-22 14:45       ` Siddhesh Poyarekar
2022-11-22 10:20   ` Siddhesh Poyarekar
2022-11-23  5:15     ` Kees Cook
2022-11-23 15:29       ` Siddhesh Poyarekar
2023-01-13 15:59   ` linux-next - bxnt buffer overflow in strnlen Niklas Cassel
2023-01-13 16:08     ` linux-next - bnxt " Niklas Cassel
2023-01-13 22:44       ` Kees Cook
2023-01-16 10:56         ` Niklas Cassel
2022-09-22 20:26 ` [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Siddhesh Poyarekar
2022-09-23  0:20   ` Kees Cook
2022-09-23  0:55     ` Siddhesh Poyarekar

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