From: Zhou Qingyang zhou1615@umn.edu
[ Upstream commit 977d2e7c63c3d04d07ba340b39987742e3241554 ]
In nonstatic_find_mem_region(), pcmcia_make_resource() is assigned to res and used in pci_bus_alloc_resource(). There 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 zhou1615@umn.edu Signed-off-by: Dominik Brodowski linux@dominikbrodowski.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 4c70e8ffe04ea..69a6e9a5d6d26 100644 --- a/drivers/pcmcia/rsrc_nonstatic.c +++ b/drivers/pcmcia/rsrc_nonstatic.c @@ -812,6 +812,9 @@ static struct resource *nonstatic_find_mem_region(u_long base, u_long num, unsigned long min, max; int ret, i, j;
+ if (!res) + return NULL; + low = low || !(s->features & SS_CAP_PAGE_REGS);
data.mask = align - 1;