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From: Maxim Kokryashkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Sergey Kaplun <skaplun@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH luajit 1/2] build: introduce LUAJIT_USE_UBSAN option
Date: Sun, 26 May 2024 12:56:28 +0300	[thread overview]
Message-ID: <z5azfxvy4zpgayckxcmvqkquz7ilaqwvvkvgfw4rjpfr6gtdbd@lfbiwesesjat> (raw)
In-Reply-To: <ZkXcdiGz0NUUyFkG@root>

Hi, Sergey!
See my thoughts below.

On Thu, May 16, 2024 at 01:14:14PM UTC, Sergey Kaplun wrote:
> Hi, folks!
> Some more thoughts below.
>
> On 15.05.24, Sergey Kaplun wrote:
>
> <snipped>
>
> > +  string(JOIN "," UBSAN_IGNORE_OPTIONS
> > +    # Misaligned pseudo-pointers are used to determine internal
> > +    # variable names inside the `for` cycle.
> > +    alignment
> > +    # Not interested in float cast overflow errors.
> > +    float-cast-overflow
> > +    # NULL checking is disabled because this is not a UB and
> > +    # raises lots of false-positive fails.
> > +    null
>
> Maybe it is worth to add also "nonnull-attribute" to the ignore options:
>
> ```
> LSAN_OPTIONS="abort_on_error=1" src/luajit -e 'error("bad usage", 3)'
> /home/burii/builds_workspace/luajit/gh-8473-ubsan/src/lj_buf.h:75:25: runtime error: null pointer passed as argument 1, which is declared to never be null
> /usr/include/string.h:44:28: note: nonnull attribute specified here
> ```
>
> Here, `memcpy()` gets the NULL pointer as the first argument and the
> `len` == 0. So there are no problems here. Also, the nullability
> violation is not a UB, as mentioned in the documentation.

It is UB, though: https://en.cppreference.com/w/cpp/string/byte/memcpy
Even with the zero len it may still cause issues, so I don't think we
should disable this check.

> Thoughts?
>
> > +    # Not interested in checking arithmetic with NULL.
> > +    pointer-overflow
> > +    # Shifts of negative numbers are widely used in parsing ULEB,
> > +    # cdata arithmetic, vmevent hash calculation, etc.
> > +    shift-base
> > +  )
>
> --
> Best regards,
> Sergey Kaplun

  reply	other threads:[~2024-05-26  9:56 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-15 12:31 [Tarantool-patches] [PATCH luajit 0/2] Add UBSan support Sergey Kaplun via Tarantool-patches
2024-05-15 12:32 ` [Tarantool-patches] [PATCH luajit 1/2] build: introduce LUAJIT_USE_UBSAN option Sergey Kaplun via Tarantool-patches
2024-05-16 10:14   ` Sergey Kaplun via Tarantool-patches
2024-05-26  9:56     ` Maxim Kokryashkin via Tarantool-patches [this message]
2024-05-27  7:22       ` Sergey Kaplun via Tarantool-patches
2024-05-27  8:28         ` Maxim Kokryashkin via Tarantool-patches
2024-06-20 10:01     ` Sergey Bronnikov via Tarantool-patches
2024-06-20 10:03       ` Sergey Kaplun via Tarantool-patches
2024-05-27  8:52   ` Maxim Kokryashkin via Tarantool-patches
2024-05-27 12:28     ` Sergey Kaplun via Tarantool-patches
2024-06-14 12:03       ` Maxim Kokryashkin via Tarantool-patches
2024-06-07 10:17   ` Sergey Bronnikov via Tarantool-patches
2024-06-13 10:56     ` Sergey Kaplun via Tarantool-patches
2024-06-13 15:13       ` Sergey Bronnikov via Tarantool-patches
2024-05-15 12:32 ` [Tarantool-patches] [PATCH luajit 2/2] ci: enable UBSan for sanitizers testing workflow Sergey Kaplun via Tarantool-patches
2024-05-26  9:50   ` Maxim Kokryashkin via Tarantool-patches
2024-05-27 12:30     ` Sergey Kaplun via Tarantool-patches
2024-06-07 10:20   ` Sergey Bronnikov via Tarantool-patches
2024-06-13 10:35     ` Sergey Kaplun via Tarantool-patches
2024-06-13 15:06       ` Sergey Bronnikov via Tarantool-patches
2024-07-09  8:06 ` [Tarantool-patches] [PATCH luajit 0/2] Add UBSan support Sergey Kaplun via Tarantool-patches

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