@@ -2125,6 +2125,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
{
unsigned long start = ULONG_MAX, end = 0;
int flush_reset = area->flags & VM_FLUSH_RESET_PERMS;
+ int flush_dmap = 0;
int i;
/*
@@ -2164,6 +2165,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
if (addr) {
start = min(addr, start);
end = max(addr + PAGE_SIZE, end);
+ flush_dmap = 1;
}
}
@@ -2173,7 +2175,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
* reset the direct map permissions to the default.
*/
set_area_direct_map(area, set_direct_map_invalid_noflush);
- _vm_unmap_aliases(start, end, 1);
+ _vm_unmap_aliases(start, end, flush_dmap);
set_area_direct_map(area, set_direct_map_default_noflush);
}
In a rare case, flush_tlb_kernel_range() could be called with a start higher than the end. In vm_remove_mappings(), in case page_address() returns 0 for all pages (for example they were all in highmem), _vm_unmap_aliases() will be called with start = ULONG_MAX, end = 0 and flush = 1. If at the same time, the vmalloc purge operation is triggered by something else while the current operation is between remove_vm_area() and _vm_unmap_aliases(), then the vm mapping just removed will be already purged. In this case the call of vm_unmap_aliases() may not find any other mappings to flush and so end up flushing start = ULONG_MAX, end = 0. So only set flush = true if we find something in the direct mapping that we need to flush, and this way this can't happen. Fixes: 868b104d7379 ("mm/vmalloc: Add flag for freeing of special permsissions") Cc: Meelis Roos <mroos@linux.ee> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Nadav Amit <namit@vmware.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> --- mm/vmalloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)