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From: "adhemerval.zanella at linaro dot org"
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To: glibc-bugs@sourceware.org
Subject: [Bug libc/25620] Signed comparison vulnerability in the ARMv7 memcpy()
Date: Mon, 16 Mar 2020 20:32:31 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D25620

Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:

           What    |Removed                     |Added
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                 CC|                            |adhemerval.zanella at lina=
ro dot o
                   |                            |rg

--- Comment #4 from Adhemerval Zanella <adhemerval.zanella at linaro dot or=
g> ---
(In reply to Yves Younan from comment #2)
> Joseph, the bug is in memcpy, not malloc.

My understanding from Joseph's reply is that using a value higher than
PTRDIFF_MAX for memcpy length is undefined behavior because either for
automatic objects or by using memory allocation functions the allocation wi=
ll
fail.=20

However, I still think it is an issue because we explicit omit mmap from the
allocation functions that might fail (if I recall correctly the reason was =
that
some programs do try to allocate more than PTRDIFF_MAX with mmap). It will =
be
still subject to the undefined behavior with pointer subtraction when opera=
ting
with the object itself, so maybe we should extend the same failure handling=
 to
mmap.

--=20
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