[klibc] malloc: Fail if block size is out of range for sbrk
sbrk() takes a parameter of type intptr_t. We allow allocating up to
PTRDIFF_MAX (equal to INPTPTR_MAX), and then add a header to that, so
the result fsize can be > INTPTR_MAX. The conversion of fsize to
intptr_t would then result in undefined behaviour (but probably
*lowering* the top of heap). Fail cleanly before that happens.
This is currently a theoretical problem since we actually use mmap()
instead of sbrk() on all architectures.
Signed-off-by: Ben Hutchings <firstname.lastname@example.org>
1 file changed