Skip to content

Fix panic on snapshot restore of stack guard pages #3823

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
celi0n wants to merge 1 commit into
base: main
Choose a base branch
from
+10 −2
Open

Fix panic on snapshot restore of stack guard pages #3823

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 10 additions & 2 deletions crates/libafl_qemu/src/modules/usermode/snapshot.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -493,7 +493,14 @@ impl SnapshotModule {

unsafe { qemu.write_mem_unchecked(*page, &data[..]) };
} else {
panic!("Cannot restored a dirty but unsaved page");
// Page was non-readable at snapshot time (e.g. a PROT_NONE guard
// page for a thread stack that glibc created before the snapshot).
// We have no saved content; zero it so subsequent runs see a clean
// state, then reset_maps will re-apply the original permissions.
if !Self::modify_mapping(qemu, new_maps, *page) {
return true; // Restore later
}
unsafe { qemu.write_mem_unchecked(*page, &SNAPSHOT_PAGE_ZEROES) };
}
}
false
Expand Down Expand Up @@ -531,7 +538,8 @@ impl SnapshotModule {
if let Some(data) = info.data.as_ref() {
unsafe { qemu.write_mem_unchecked(*page, &data[..]) };
} else {
panic!("Cannot restored a dirty but unsaved page");
// Non-readable at snapshot time; zero it.
unsafe { qemu.write_mem_unchecked(*page, &SNAPSHOT_PAGE_ZEROES) };
}
}
}
Expand Down
Loading