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? Regards, Len
