mm/list_lru.c: prefer struct_size over open coded arithmetic

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.

So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kvmalloc() functions.

Also, take the opportunity to refactor the memcpy() call to use the
flex_array_size() helper.

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

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Len Baker <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions