Hi Jani, On Mon, Oct 18, 2021 at 01:00:01PM +0300, Jani Nikula wrote: > On Sat, 16 Oct 2021, Len Baker <len.baker@xxxxxxx> wrote: > > Hi Daniel and Jani, > > > > On Wed, Oct 13, 2021 at 01:51:30PM +0200, Daniel Vetter wrote: > >> On Wed, Oct 13, 2021 at 02:24:05PM +0300, Jani Nikula wrote: > >> > On Mon, 11 Oct 2021, Len Baker <len.baker@xxxxxxx> wrote: > >> > > Hi, > >> > > > >> > > On Sun, Oct 03, 2021 at 12:42:58PM +0200, Len Baker wrote: > >> > >> As noted in the "Deprecated Interfaces, Language Features, Attributes, > >> > >> and Conventions" documentation [1], size calculations (especially > >> > >> multiplication) should not be performed in memory allocator (or similar) > >> > >> function arguments due to the risk of them overflowing. This could lead > >> > >> to values wrapping around and a smaller allocation being made than the > >> > >> caller was expecting. Using those allocations could lead to linear > >> > >> overflows of heap memory and other misbehaviors. > >> > >> > >> > >> In this case these are not actually dynamic sizes: all the operands > >> > >> involved in the calculation are constant values. However it is better to > >> > >> refactor them anyway, just to keep the open-coded math idiom out of > >> > >> code. > >> > >> > >> > >> So, add at the end of the struct i915_syncmap a union with two flexible > >> > >> array members (these arrays share the same memory layout). This is > >> > >> possible using the new DECLARE_FLEX_ARRAY macro. And then, use the > >> > >> struct_size() helper to do the arithmetic instead of the argument > >> > >> "size + count * size" in the kmalloc and kzalloc() functions. > >> > >> > >> > >> Also, take the opportunity to refactor the __sync_seqno and __sync_child > >> > >> making them more readable. > >> > >> > >> > >> This code was detected with the help of Coccinelle and audited and fixed > >> > >> manually. > >> > >> > >> > >> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > >> > >> > >> > >> Signed-off-by: Len Baker <len.baker@xxxxxxx> > >> > >> --- > >> > >> drivers/gpu/drm/i915/i915_syncmap.c | 12 ++++++++---- > >> > >> 1 file changed, 8 insertions(+), 4 deletions(-) > >> > > > >> > > I received a mail telling that this patch doesn't build: > >> > > > >> > > == Series Details == > >> > > > >> > > Series: drm/i915: Prefer struct_size over open coded arithmetic > >> > > URL : https://patchwork.freedesktop.org/series/95408/ > >> > > State : failure > >> > > > >> > > But it builds without error against linux-next (tag next-20211001). Against > >> > > which tree and branch do I need to build? > >> > > >> > drm-tip [1]. It's a sort of linux-next for graphics. I think there are > >> > still some branches that don't feed to linux-next. > >> > >> Yeah we need to get gt-next in linux-next asap. Joonas promised to send > >> out his patch to make that happen in dim. > >> -Daniel > > > > Is there a possibility that you give an "Acked-by" tag? And then this patch > > goes to the mainline through the Kees' tree or Gustavo's tree? > > If this does not apply to drm-intel-gt-next (or drm-tip), applying it to > some other branch will just cause unnecessary conflicts later on. It's > unnecessary extra work. It's not an urgent fix or anything, there is no > reason to do that. So that's a NAK. Ok. Understood. > > Or is it better to wait for drm-tip to update? > > drm-tip is up to date, it's just that one of the branches that feed to > it is (was?) not feeding to linux-next. Sorry, but I'm missing something here. In linux-next this is the commit history of include/linux/stddef.h file: 3080ea5553cc stddef: Introduce DECLARE_FLEX_ARRAY() helper 50d7bd38c3aa stddef: Introduce struct_group() helper macro e7f18c22e6be stddef: Fix kerndoc for sizeof_field() and offsetofend() 4229a470175b stddef.h: Introduce sizeof_field() ... But in drm-tip this is the commit history: 4229a470175b stddef.h: Introduce sizeof_field() ... For this patch the DECLARE_FLEX_ARRAY() helper is needed. But the build fails due to the last tree commits for stddef.h file are not present. So, if I understand correctly, drm-tip is not up to date with linux-next. Regards, Len > > If you're contributing to drm, please consider basing your patches on > top of drm-tip. > > > BR, > Jani. > > > > > > Regards, > > Len > > > >> > >> > > >> > BR, > >> > Jani. > >> > > >> > > >> > [1] https://cgit.freedesktop.org/drm/drm-tip > >> > > >> > > >> > > > >> > > Regards, > >> > > Len > >> > > >> > -- > >> > Jani Nikula, Intel Open Source Graphics Center > >> > >> -- > >> Daniel Vetter > >> Software Engineer, Intel Corporation > >> http://blog.ffwll.ch > > -- > Jani Nikula, Intel Open Source Graphics Center
