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Re: RFC: __attribute_alloc_size__ on allocation functions (BZ#23741)
- From: Zack Weinberg <zackw at panix dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 9 Nov 2018 10:36:36 -0500
- Subject: Re: RFC: __attribute_alloc_size__ on allocation functions (BZ#23741)
- References: <aa9e2a38-2dc3-11a9-711b-412b10260830@linaro.org>
On Fri, Nov 9, 2018 at 10:11 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> BZ#23741 suggests glibc adds gcc __attribute_alloc_size__ on malloc functions
> so asking allocation larger than PTRDIFF_MAX emits a warning that the value
> exceeds maximum object size.
I think it makes sense to add the annotations and disallow allocations
larger than PTRDIFF_MAX for malloc and its family, but *not* for mmap,
brk, sbrk, and any other hypothetical system memory-allocation
primitives (IIRC Mach has something else) because those are not
necessarily used to allocate "objects" in the sense of the C standard,
and we know from other cases that people don't like it when glibc's
system call wrappers impose restrictions that the bare system call
doesn't.
zw