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Align addresses before calling qemu.unmap in Snapshot module (#2978)

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* alignment

* a
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Dongjia "toka" Zhang 2025-02-13 14:17:48 +01:00 committed by GitHub
parent cb471a9282
commit b067435862
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1 changed files with 13 additions and 5 deletions
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14
libafl_qemu/src/modules/usermode/snapshot.rs
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@ -415,12 +415,20 @@ impl SnapshotModule {
.unwrap(); .unwrap();
} else if new_brk > self.brk { } else if new_brk > self.brk {
// The heap has grown. so we want to drop those // The heap has grown. so we want to drop those
let drop_sz = (new_brk - self.brk) as usize; // we want to align the addresses before calling unmap
// although it is very unlikely that the brk has an unaligned value
let new_page_boundary = (new_brk + ((SNAPSHOT_PAGE_MASK - 1) as GuestAddr))
& (!(SNAPSHOT_PAGE_SIZE - 1) as GuestAddr);
let old_page_boundary = (self.brk + ((SNAPSHOT_PAGE_MASK - 1) as GuestAddr))
& (!(SNAPSHOT_PAGE_SIZE - 1) as GuestAddr);
if new_page_boundary != old_page_boundary {
let unmap_sz = (new_page_boundary - old_page_boundary) as usize;
// if self.brk is not aligned this call will return an error // if self.brk is not aligned this call will return an error
// and it will page align this drop_sz too // and it will page align this unmap_sz too (but it is already aligned for us)
// look at target_munmap in qemu-libafl-bridge // look at target_munmap in qemu-libafl-bridge
qemu.unmap(self.brk, drop_sz).unwrap(); qemu.unmap(self.brk, unmap_sz).unwrap();
}
} }
for acc in &mut self.accesses { for acc in &mut self.accesses {