linux-kernel - [PATCH 4.15 004/146] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry

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Date:   Tue, 13 Mar 2018 16:22:51 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+1a240cdb1f4cc88819df@...kaller.appspotmail.com,
        Michal Hocko <mhocko@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Matthew Wilcox <willy@...radead.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        akpm@...ux-foundation.org, dhowells@...hat.com, hannes@...xchg.org,
        Jason Wang <jasowang@...hat.com>
Subject: [PATCH 4.15 004/146] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry_alloc()

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wang <jasowang@...hat.com>

commit 7fc17e909edfb9bf421ee04e981d3d474175c7c7 upstream.

There're several implications after commit 0bf7800f1799 ("ptr_ring:
try vmalloc() when kmalloc() fails") with the using of vmalloc() since
can't allow GFP_ATOMIC but mandate GFP_KERNEL. This will lead a WARN
since cpumap try to call with GFP_ATOMIC. Fortunately, entry
allocation of cpumap can only be done through syscall path which means
GFP_ATOMIC is not necessary, so fixing this by replacing GFP_ATOMIC
with GFP_KERNEL.

Reported-by: syzbot+1a240cdb1f4cc88819df@...kaller.appspotmail.com
Fixes: 0bf7800f1799 ("ptr_ring: try vmalloc() when kmalloc() fails")
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Jesper Dangaard Brouer <brouer@...hat.com>
Cc: akpm@...ux-foundation.org
Cc: dhowells@...hat.com
Cc: hannes@...xchg.org
Signed-off-by: Jason Wang <jasowang@...hat.com>
Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/bpf/cpumap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -339,7 +339,7 @@ static int cpu_map_kthread_run(void *dat
 
 struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu, int map_id)
 {
-	gfp_t gfp = GFP_ATOMIC|__GFP_NOWARN;
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
 	struct bpf_cpu_map_entry *rcpu;
 	int numa, err;