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Kernel: Make msync return EINVAL when regions are too large

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As a small cleanup, this also makes `page_round_up` verify its
precondition with `page_round_up_would_wrap` (which callers are expected
to call), rather than having its own logic.

Fixes #11297.
This commit is contained in:
Guilherme Gonçalves 2021-12-22 10:42:27 -03:00 • committed by Brian Gianforcaro
parent 615c2cbcce
commit da6aef9fff
2 changed files with 6 additions and 4 deletions
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6
Kernel/Memory/MemoryManager.h
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@ -31,10 +31,8 @@ constexpr bool page_round_up_would_wrap(FlatPtr x)
constexpr FlatPtr page_round_up(FlatPtr x) constexpr FlatPtr page_round_up(FlatPtr x)
{ {
FlatPtr rounded = (((FlatPtr)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1)); VERIFY(!page_round_up_would_wrap(x));
// Rounding up >0xfffff000 wraps back to 0. That's never what we want. return (((FlatPtr)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1));
VERIFY(x == 0 || rounded != 0);
return rounded;
} }
constexpr FlatPtr page_round_down(FlatPtr x) constexpr FlatPtr page_round_down(FlatPtr x)

4
Kernel/Syscalls/mmap.cpp
View file

@ -587,6 +587,10 @@ ErrorOr<FlatPtr> Process::sys$msync(Userspace<void*> address, size_t size, int f
if (address.ptr() % PAGE_SIZE != 0) if (address.ptr() % PAGE_SIZE != 0)
return EINVAL; return EINVAL;
if (Memory::page_round_up_would_wrap(size)) {
return EINVAL;
}
// Note: This is not specified // Note: This is not specified
size = Memory::page_round_up(size); size = Memory::page_round_up(size);