* Pedro Falcato pedro.falcato@gmail.com [240816 20:19]:
Delegate all can_modify checks to the proper places. Unmap checks are done in do_unmap (et al). The source VMA check is done purposefully before unmapping, to keep the original mseal semantics.
Signed-off-by: Pedro Falcato pedro.falcato@gmail.com
Reviewed-by: Liam R. Howlett Liam.Howlett@Oracle.com
mm/mremap.c | 32 ++++++-------------------------- 1 file changed, 6 insertions(+), 26 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c index e7ae140fc640..24712f8dbb6b 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -902,19 +902,6 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, if ((mm->map_count + 2) >= sysctl_max_map_count - 3) return -ENOMEM;
- /*
* In mremap_to().* Move a VMA to another location, check if src addr is sealed.** Place can_modify_mm here because mremap_to()* does its own checking for address range, and we only* check the sealing after passing those checks.** can_modify_mm assumes we have acquired the lock on MM.*/- if (unlikely(!can_modify_mm(mm, addr, addr + old_len)))
return -EPERM;- if (flags & MREMAP_FIXED) { /*
- In mremap_to().
@@ -1052,6 +1039,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, goto out; }
- /* Don't allow remapping vmas when they have already been sealed */
- if (!can_modify_vma(vma)) {
ret = -EPERM;goto out;- }
- if (is_vm_hugetlb_page(vma)) { struct hstate *h __maybe_unused = hstate_vma(vma);
@@ -1079,19 +1072,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, goto out; }
- /*
* Below is shrink/expand case (not mremap_to())* Check if src address is sealed, if so, reject.* In other words, prevent shrinking or expanding a sealed VMA.** Place can_modify_mm here so we can keep the logic related to* shrink/expand together.*/- if (unlikely(!can_modify_mm(mm, addr, addr + old_len))) {
ret = -EPERM;goto out;- }
- /*
- Always allow a shrinking remap: that just unmaps
- the unnecessary pages..
-- 2.46.0