From: u-uy74@aetey.se
To: musl@lists.openwall.com
Subject: "non-float" malloc (was: incompatibility between libtheora/mmx and musl)
Date: Sun, 2 Oct 2016 12:59:50 +0200 [thread overview]
Message-ID: <20161002105950.GM28325@example.net> (raw)
In-Reply-To: <20160914144145.GT1280@port70.net>
Hello Szabolcs,
On Wed, Sep 14, 2016 at 04:41:45PM +0200, Szabolcs Nagy wrote:
> this might be an issue:
> musl uses float instructions in malloc,
> if mmx needs different fpu state and
> they don't change it back for a malloc
> call that can corrupt the heap.
>
> to test this, try to use the 'non-float bin index'
> code in musl from here:
> http://port70.net/~nsz/musl/malloc.c
Thanks again for the solution to the libtheora mystery.
Now I have reported the same issue affecting ffmpeg, it contains quite
a bit of simd assembler code and assumed until now among others that
malloc() never uses floating point.
Hopefully a fix is on the way there.
For the time being, to have a working ffmpeg build,
I tried to use your "non-float" malloc.
Unfortunately this leads to a segfault when used with the explicit runtime
loader, because brk() happily grows over the dynamic loader's data.
The modified variant of the malloc code seems to not apply
the traverses_stack_p() check.
I guess as long as you want to keep the special malloc.c
you would like it to be robust.
Would you mind adding the brk()/stack overlap checking to this variant
of the code?
Regards,
Rune
next prev parent reply other threads:[~2016-10-02 10:59 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 18:06 incompatibility between libtheora/mmx and musl ? u-uy74
2016-09-13 19:20 ` Markus Wichmann
2016-09-13 20:41 ` Rich Felker
2016-09-13 20:43 ` Rich Felker
2016-09-14 10:32 ` u-uy74
2016-09-14 11:24 ` Szabolcs Nagy
2016-09-14 14:04 ` u-uy74
2016-09-14 14:28 ` Rich Felker
2016-09-14 14:31 ` Timo Teras
2016-09-14 14:39 ` Rich Felker
2016-09-14 14:40 ` Rich Felker
2016-09-14 14:41 ` Szabolcs Nagy
2016-09-14 15:11 ` u-uy74
2016-10-02 10:59 ` u-uy74 [this message]
2016-10-02 11:17 ` "non-float" malloc (was: incompatibility between libtheora/mmx and musl) u-uy74
2016-10-02 12:08 ` Szabolcs Nagy
2016-10-02 12:24 ` u-uy74
2016-10-02 13:24 ` u-uy74
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