From: Alistair Popple <apopple@xxxxxxxxxx> Subject: kernel/resource: fix return code check in __request_free_mem_region Splitting an earlier version of a patch that allowed calling __request_region() while holding the resource lock into a series of patches required changing the return code for the newly introduced __request_region_locked(). Unfortunately this change was not carried through to a subsequent commit 56fd94919b8b ("kernel/resource: fix locking in request_free_mem_region") in the series. This resulted in a use-after-free due to freeing the struct resource without properly releasing it. Fix this by correcting the return code check so that the struct is not freed if the request to add it was successful. Link: https://lkml.kernel.org/r/20210512073528.22334-1-apopple@xxxxxxxxxx Fixes: 56fd94919b8b ("kernel/resource: fix locking in request_free_mem_region") Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Balbir Singh <bsingharora@xxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Cc: John Hubbard <jhubbard@xxxxxxxxxx> Cc: Muchun Song <smuchun@xxxxxxxxx> Cc: Oliver Sang <oliver.sang@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/resource.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/resource.c~kernel-resource-fix-return-code-check-in-__request_free_mem_region +++ a/kernel/resource.c @@ -1805,7 +1805,7 @@ static struct resource *__request_free_m REGION_DISJOINT) continue; - if (!__request_region_locked(res, &iomem_resource, addr, size, + if (__request_region_locked(res, &iomem_resource, addr, size, name, 0)) break; _