From: Nadav Amit <namit@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: fix find_next_iomem_res() documentation] Link: http://lkml.kernel.org/r/20190613045903.4922-2-namit@xxxxxxxxxx Fixes: ff3cc952d3f00 ("resource: Add remove_resource interface") Signed-off-by: Nadav Amit <namit@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Toshi Kani <toshi.kani@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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, _
