powerpc/vas: Fix potential NULL pointer dereference

commit 61cb9ac66b30374c7fd8a8b2a3c4f8f432c72e36 upstream.

(!ptr && !ptr->foo) strikes again. :)

The expression (!ptr && !ptr->foo) is bogus and in case ptr is NULL,
it leads to a NULL pointer dereference: ptr->foo.

Fix this by converting && to ||

This issue was detected with the help of Coccinelle, and audited and
fixed manually.

Fixes: 1a0d0d5ed5e3 ("powerpc/vas: Add platform specific user window operations")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015050345.GA1161918@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index 30172e52e16b713e0a330986c3e1b4e86826470b..4d82c92ddd52301e1c4044898b80acb54a7cf835 100644 (file)
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -303,7 +303,7 @@ static int coproc_ioc_tx_win_open(struct file *fp, unsigned long arg)
                return -EINVAL;
        }
 
-       if (!cp_inst->coproc->vops && !cp_inst->coproc->vops->open_win) {
+       if (!cp_inst->coproc->vops || !cp_inst->coproc->vops->open_win) {
                pr_err("VAS API is not registered\n");
                return -EACCES;
        }
@@ -373,7 +373,7 @@ static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
                return -EINVAL;
        }
 
-       if (!cp_inst->coproc->vops && !cp_inst->coproc->vops->paste_addr) {
+       if (!cp_inst->coproc->vops || !cp_inst->coproc->vops->paste_addr) {
                pr_err("%s(): VAS API is not registered\n", __func__);
                return -EACCES;
        }