On Mon, Nov 28, 2016 at 09:39:31AM -0500, Neil Horman wrote:

On Mon, Nov 28, 2016 at 03:33:40PM +0100, Andrey Konovalov wrote:

quoted

On Mon, Nov 28, 2016 at 3:13 PM, Neil Horman [off-list ref] wrote:

quoted

On Mon, Nov 28, 2016 at 02:00:19PM +0100, Andrey Konovalov wrote:

quoted

Hi!

I've got the following error report while running the syzkaller fuzzer.

On commit d8e435f3ab6fea2ea324dce72b51dd7761747523 (Nov 26).

A reproducer is attached.

a.out: vmalloc: allocation failure, allocated 823562240 of 1427091456
bytes, mode:0x24000c2(GFP_KERNEL|__GFP_HIGHMEM)

How much total ram do you have in this system?  The call appears to be
attempting to allocate 1.3 Gb of data.  Even using vmalloc to allow
discontiguous allocation, thats alot of memory, and if enough is in use already,
I could make the argument that this might be expected behavior.

Hi Neail,

I have 2 Gb.

That would be why.  Allocating 65% of the available system memory will almost
certainly lead to OOM failures quickly.

quoted

Just tested with 4 Gb, everything seems to be working fine.
So I guess this is not actually a bug and allocating 1.3 Gb is OK.

Still we probably should avoid the warn triggered by an userspace
application: (untested)

--8<--

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index fc4977456c30..b56a0e128fc3 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c

@@ -958,7 +958,8 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size)
 	if (sz <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
 		info = kmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
 	if (!info) {
-		info = vmalloc(sz);
+		info = __vmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_HIGHMEM,
+				 PAGE_KERNEL);
 		if (!info)
 			return NULL;
 	}