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Fix panic in `Vmar::protect` due to in-place merge during iteration 

Signed-off-by: raylee <hburaylee@gmail.com>
This commit is contained in:
raylee 2026-01-22 13:36:42 +00:00
parent b7ae738310
commit e4e661a220
1 changed files with 59 additions and 19 deletions
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78
kernel/src/vm/vmar/vmar_impls/protect.rs
View File

@ -21,31 +21,62 @@ impl Vmar {
let mut inner = self.inner.write();
let vm_space = self.vm_space();
let mut protect_mappings = Vec::new();
// Step 1: Validate mappings and collect their start addresses
let mut starts = Vec::new();
let mut last_end = range.start;
let mut actual_end = range.start;
for vm_mapping in inner.vm_mappings.find(&range) {
protect_mappings.push((vm_mapping.range(), vm_mapping.perms()))
let r = vm_mapping.range();
// Check for gaps between mappings
if last_end < r.start {
actual_end = last_end;
break;
}
starts.push(r.start);
last_end = r.end;
}
let mut last_mapping_end = range.start;
for (vm_mapping_range, vm_mapping_perms) in protect_mappings {
if last_mapping_end < vm_mapping_range.start {
return_errno_with_message!(
Errno::ENOMEM,
"the range contains pages that are not mapped"
);
}
last_mapping_end = vm_mapping_range.end;
if actual_end == range.start {
actual_end = last_end;
}
if perms == vm_mapping_perms & VmPerms::ALL_PERMS {
// Determine if the full range is covered
let full_range_covered = actual_end >= range.end;
let protect_end = if full_range_covered {
range.end
} else {
actual_end
};
if protect_end == range.start {
return_errno_with_message!(
Errno::ENOMEM,
"the range contains pages that are not mapped"
);
}
// Step 2: Remove all affected mappings from the tree
let mut mappings = Vec::new();
for start in starts {
if let Some(m) = inner.remove(&start) {
mappings.push(m);
}
}
// Step 3: Process each mapping - split, protect, and reinsert
let protect_range = range.start..protect_end;
for vm_mapping in mappings {
let vm_mapping_range = vm_mapping.range();
let intersected_range = get_intersected_range(&protect_range, &vm_mapping_range);
if intersected_range.start == intersected_range.end {
inner.insert_try_merge(vm_mapping);
continue;
}
let new_perms = perms | (vm_mapping_perms & VmPerms::ALL_MAY_PERMS);
new_perms.check()?;
let vm_mapping = inner.remove(&vm_mapping_range.start).unwrap();
let vm_mapping_range = vm_mapping.range();
let intersected_range = get_intersected_range(&range, &vm_mapping_range);
// Protects part of the taken `VmMapping`.
let (left, taken, right) = vm_mapping.split_range(&intersected_range);
@ -58,12 +89,21 @@ impl Vmar {
inner.insert_without_try_merge(right);
}
let old_perms = taken.perms();
if perms == (old_perms & VmPerms::ALL_PERMS) {
inner.insert_try_merge(taken);
continue;
}
let new_perms = perms | (old_perms & VmPerms::ALL_MAY_PERMS);
new_perms.check()?;
// Protects part of the `VmMapping`.
let taken = taken.protect(vm_space.as_ref(), new_perms);
inner.insert_try_merge(taken);
}
if last_mapping_end < range.end {
if !full_range_covered {
return_errno_with_message!(
Errno::ENOMEM,
"the range contains pages that are not mapped"