Re: [PATCH] um: Fix some error handling in uml_vector_user_bpf()

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On 24/01/2020 16:44, Dan Carpenter wrote:
On Fri, Jan 24, 2020 at 12:52:18PM +0000, Anton Ivanov wrote:


On 24/01/2020 10:14, Dan Carpenter wrote:
1) The uml_vector_user_bpf() returns pointers so it should return NULL
     instead of false.
2) If the "bpf_prog" allocation failed, it would have eventually lead to
     a crash.  We can't succeed after the error happens so it should just
     return.

Fixes: 9807019a62dc ("um: Loadable BPF "Firmware" for vector drivers")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
   arch/um/drivers/vector_user.c | 10 +++++-----
   1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index ddcd917be0af..88483f5b034c 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -732,13 +732,13 @@ void *uml_vector_user_bpf(char *filename)
   	if (stat(filename, &statbuf) < 0) {
   		printk(KERN_ERR "Error %d reading bpf file", -errno);
-		return false;
+		return NULL;

I will sort this one out, thanks for noticing.

   	}
   	bpf_prog = uml_kmalloc(sizeof(struct sock_fprog), UM_GFP_KERNEL);
-	if (bpf_prog != NULL) {
-		bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
-		bpf_prog->filter = NULL;
-	}
+	if (!pfg_prog)

^^^^^ ?

If we don't return here it leads to a NULL dereference.

It says pfg_prog

I cannot find this identifier :)


regards,
dan carpenter


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--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/



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