diff options
| -rw-r--r-- | Kernel/Syscalls/mmap.cpp | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Kernel/Syscalls/mmap.cpp b/Kernel/Syscalls/mmap.cpp index 065c8add69..ef380d3db8 100644 --- a/Kernel/Syscalls/mmap.cpp +++ b/Kernel/Syscalls/mmap.cpp @@ -325,7 +325,7 @@ ErrorOr<FlatPtr> Process::sys$mprotect(Userspace<void*> addr, size_t size, int p if (const auto& regions = address_space().find_regions_intersecting(range_to_mprotect); regions.size()) { size_t full_size_found = 0; - // first check before doing anything + // Check that all intersecting regions are compatible. for (const auto* region : regions) { if (!region->is_mmap()) return EPERM; @@ -341,13 +341,14 @@ ErrorOr<FlatPtr> Process::sys$mprotect(Userspace<void*> addr, size_t size, int p if (full_size_found != range_to_mprotect.size()) return ENOMEM; - // then do all the other stuff + // Finally, iterate over each region, either updating its access flags if the range covers it wholly, + // or carving out a new subregion with the appropriate access flags set. for (auto* old_region : regions) { if (old_region->access() == Memory::prot_to_region_access_flags(prot)) continue; const auto intersection_to_mprotect = range_to_mprotect.intersect(old_region->range()); - // full sub region + // If the region is completely covered by range, simply update the access flags if (intersection_to_mprotect == old_region->range()) { old_region->set_readable(prot & PROT_READ); old_region->set_writable(prot & PROT_WRITE); @@ -367,7 +368,8 @@ ErrorOr<FlatPtr> Process::sys$mprotect(Userspace<void*> addr, size_t size, int p // We need to allocate a new region for the range we wanted to change permission bits on. auto adjacent_regions = TRY(address_space().try_split_region_around_range(*old_region, intersection_to_mprotect)); - // there should only be one + // Since the range is not contained in a single region, it can only partially cover its starting and ending region, + // therefore carving out a chunk from the region will always produce a single extra region, and not two. VERIFY(adjacent_regions.size() == 1); size_t new_range_offset_in_vmobject = old_region->offset_in_vmobject() + (intersection_to_mprotect.base().get() - old_region->range().base().get()); |