From 7756cb45dbfe65af431c555e30e9a030272b4f45 Mon Sep 17 00:00:00 2001 From: Zhou Qingyang Date: Wed, 1 Dec 2021 00:59:23 +0800 Subject: [PATCH] pcmcia: rsrc_nonstatic: Fix a NULL pointer dereference in __nonstatic_find_io_region() [ Upstream commit ca0fe0d7c35c97528bdf621fdca75f13157c27af ] In __nonstatic_find_io_region(), pcmcia_make_resource() is assigned to res and used in pci_bus_alloc_resource(). There is a dereference of res in pci_bus_alloc_resource(), which could lead to a NULL pointer dereference on failure of pcmcia_make_resource(). Fix this bug by adding a check of res. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_PCCARD_NONSTATIC=y show no new warnings, and our static analyzer no longer warns about this code. Fixes: 49b1153adfe1 ("pcmcia: move all pcmcia_resource_ops providers into one module") Signed-off-by: Zhou Qingyang [linux@dominikbrodowski.net: Fix typo in commit message] Signed-off-by: Dominik Brodowski Signed-off-by: Sasha Levin --- drivers/pcmcia/rsrc_nonstatic.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pcmcia/rsrc_nonstatic.c b/drivers/pcmcia/rsrc_nonstatic.c index bb15a8b..827ca6e9 100644 --- a/drivers/pcmcia/rsrc_nonstatic.c +++ b/drivers/pcmcia/rsrc_nonstatic.c @@ -690,6 +690,9 @@ static struct resource *__nonstatic_find_io_region(struct pcmcia_socket *s, unsigned long min = base; int ret; + if (!res) + return NULL; + data.mask = align - 1; data.offset = base & data.mask; data.map = &s_data->io_db; -- 2.7.4