From: Nadav Amit namit@vmware.com Subject: resource: fix locking in find_next_iomem_res()

Since resources can be removed, locking should ensure that the resource is not removed while accessing it. However, find_next_iomem_res() does not hold the lock while copying the data of the resource.

Keep holding the lock while the data is copied. While at it, change the return value to a more informative value. It is disregarded by the callers.

[akpm@linux-foundation.org: fix find_next_iomem_res() documentation] Link: http://lkml.kernel.org/r/20190613045903.4922-2-namit@vmware.com Fixes: ff3cc952d3f00 ("resource: Add remove_resource interface") Signed-off-by: Nadav Amit namit@vmware.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: Dan Williams dan.j.williams@intel.com Cc: Borislav Petkov bp@suse.de Cc: Toshi Kani toshi.kani@hpe.com Cc: Peter Zijlstra peterz@infradead.org Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Bjorn Helgaas bhelgaas@google.com Cc: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

kernel/resource.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/kernel/resource.c~resource-fix-locking-in-find_next_iomem_res +++ a/kernel/resource.c @@ -326,7 +326,7 @@ EXPORT_SYMBOL(release_resource); * * If a resource is found, returns 0 and @*res is overwritten with the part * of the resource that's within [@start..@end]; if none is found, returns - * -1 or -EINVAL for other invalid parameters. + * -ENODEV. Returns -EINVAL for invalid parameters. * * This function walks the whole tree and not just first level children * unless @first_lvl is true. @@ -365,16 +365,16 @@ static int find_next_iomem_res(resource_ break; }

- read_unlock(&resource_lock); - if (!p) - return -1; + if (p) { + /* copy data */ + res->start = max(start, p->start); + res->end = min(end, p->end); + res->flags = p->flags; + res->desc = p->desc; + }

- /* copy data */ - res->start = max(start, p->start); - res->end = min(end, p->end); - res->flags = p->flags; - res->desc = p->desc; - return 0; + read_unlock(&resource_lock); + return p ? 0 : -ENODEV; }

static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end, _