From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Pretty much similar to commit 1336c662474e
("bpf: Clear per_cpu pointers during bpf_prog_realloc") we also need to
clear these two percpu pointers in bpf_prog_clone_create(), otherwise
would get a double free:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 13 PID: 8140 Comm: kworker/13:247 Kdump: loaded Tainted: G W OE
5.11.0-rc4.bm.1-amd64+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
test_bpf: #1 TXA
Workqueue: events bpf_prog_free_deferred
RIP: 0010:percpu_ref_get_many.constprop.97+0x42/0xf0
Code: [...]
RSP: 0018:ffffa6bce1f9bda0 EFLAGS: 00010002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000021dfc7b
RDX: ffffffffae2eeb90 RSI: 867f92637e338da5 RDI: 0000000000000046
RBP: ffffa6bce1f9bda8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000046 R11: 0000000000000000 R12: 0000000000000280
R13: 0000000000000000 R14: 0000000000000000 R15: ffff9b5f3ffdedc0
FS: 0000000000000000(0000) GS:ffff9b5f2fb40000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000027c36c002 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
refill_obj_stock+0x5e/0xd0
free_percpu+0xee/0x550
__bpf_prog_free+0x4d/0x60
process_one_work+0x26a/0x590
worker_thread+0x3c/0x390
? process_one_work+0x590/0x590
kthread+0x130/0x150
? kthread_park+0x80/0x80
ret_from_fork+0x1f/0x30
This bug is 100% reproducible with test_kmod.sh.
Reported-by: Jiang Wang <jiang.wang@xxxxxxxxxxxxx>
Fixes: 700d4796ef59 ("bpf: Optimize program stats")
Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism")
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
---
kernel/bpf/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 0ae015ad1e05..b0c11532e535 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1103,6 +1103,8 @@ static struct bpf_prog *bpf_prog_clone_create(struct bpf_prog *fp_other,
* this still needs to be adapted.
*/
memcpy(fp, fp_other, fp_other->pages * PAGE_SIZE);
+ fp_other->stats = NULL;
+ fp_other->active = NULL;
}
return fp;
--
2.25.1
