[PATCH Fix 2/2] kernel/fork: Detect mas_store() failure in dup_mmap()

[Liam Howlett]

mas_store() should not fail, but protect against potential failures by
checking the maple state for mas_is_err().

Fixes: 57579b57de57 (kernel/fork: use maple tree for dup_mmap() during forking)
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
 kernel/fork.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index 2d7ce88da540..dfa2d5d22ed1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -685,6 +685,8 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 		mas.index = tmp->vm_start;
 		mas.last = tmp->vm_end - 1;
 		mas_store(&mas, tmp);
+		if (mas_is_err(&mas))
+			goto fail_nomem_mas_store;
 
 		mm->map_count++;
 		if (!(tmp->vm_flags & VM_WIPEONFORK))
@@ -708,6 +710,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 fail_uprobe_end:
 	uprobe_end_dup_mmap();
 	return retval;
+
+fail_nomem_mas_store:
+	unlink_anon_vmas(tmp);
 fail_nomem_anon_vma_fork:
 	mpol_put(vma_policy(tmp));
 fail_nomem_policy:
-- 
2.35.1