MIPS: VPE loader: Check vmalloc return value in vpe_open

The return value of the vmalloc() call in arch/mips/kernel/vpe.c::vpe_open()
is not checked, so we potentially store a null pointer in v->pbuffer.  Add
a check for a null return and then return -ENOMEM in that case.

[Ralf: The check added by Jesper's original patch is where it logically
should be.  Adding it eleminated the need for the checks in a few other
places, so I removed them.  There still is a zillion of other things that
need to be fixed in this file / API.]

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1747/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 6 insertions, 8 deletions

diff --git a/arch/mips/kernel/vpe.c b/arch/mips/kernel/vpe.c
index 3eb3cde2f661..6a1fdfef8fde 100644
--- a/arch/mips/kernel/vpe.c
+++ b/arch/mips/kernel/vpe.c
@@ -1092,6 +1092,10 @@ static int vpe_open(struct inode *inode, struct file *filp)
 
         /* this of-course trashes what was there before... */
         v->pbuffer = vmalloc(P_SIZE);
+        if (!v->pbuffer) {
+                pr_warning("VPE loader: unable to allocate memory\n");
+                return -ENOMEM;
+        }
         v->plen = P_SIZE;
         v->load_addr = NULL;
         v->len = 0;
@@ -1149,10 +1153,9 @@ static int vpe_release(struct inode *inode, struct file *filp)
         if (ret < 0)
                 v->shared_ptr = NULL;
 
-        // cleanup any temp buffers
-        if (v->pbuffer)
-                vfree(v->pbuffer);
+        vfree(v->pbuffer);
         v->plen = 0;
+
         return ret;
 }
 
@@ -1169,11 +1172,6 @@ static ssize_t vpe_write(struct file *file, const char __user * buffer,
         if (v == NULL)
                 return -ENODEV;
 
-        if (v->pbuffer == NULL) {
-                printk(KERN_ERR "VPE loader: no buffer for program\n");
-                return -ENOMEM;
-        }
-
         if ((count + v->len) > v->plen) {
                 printk(KERN_WARNING
                        "VPE loader: elf size too big. Perhaps strip uneeded symbols\n");