Date: Wed, 14 Feb 2018 12:45:52 -0800 From: Joe Perches <joe@...ches.com> To: Matthew Wilcox <willy@...radead.org>, Andrew Morton <akpm@...ux-foundation.org> Cc: Matthew Wilcox <mawilcox@...rosoft.com>, linux-mm@...ck.org, Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: Re: [PATCH v2 2/8] mm: Add kvmalloc_ab_c and kvzalloc_struct On Wed, 2018-02-14 at 12:11 -0800, Matthew Wilcox wrote: > From: Matthew Wilcox <mawilcox@...rosoft.com> > > We have kvmalloc_array in order to safely allocate an array with a > number of elements specified by userspace (avoiding arithmetic overflow > leading to a buffer overrun). But it's fairly common to have a header > in front of that array (eg specifying the length of the array), so we > need a helper function for that situation. > > kvmalloc_ab_c() is the workhorse that does the calculation, but in spite > of our best efforts to name the arguments, it's really hard to remember > which order to put the arguments in. kvzalloc_struct() eliminates that > effort; you tell it about the struct you're allocating, and it puts the > arguments in the right order for you (and checks that the arguments > you've given are at least plausible). > > For comparison between the three schemes: > > sev = kvzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, > GFP_KERNEL); > sev = kvzalloc_ab_c(elems, sizeof(struct v4l2_kevent), sizeof(*sev), > GFP_KERNEL); > sev = kvzalloc_struct(sev, events, elems, GFP_KERNEL); Perhaps kv[zm]alloc_buf_and_array is better naming.
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