After commit a2c11b034142 ("kcm: use BPF_PROG_RUN")
syzbot easily triggers the warning in cant_sleep().
As explained in commit 6cab5e90ab2b ("bpf: run bpf programs
with preemption disabled") we need to disable preemption before
running bpf programs.
BUG: assuming atomic context at net/kcm/kcmsock.c:382
in_atomic(): 0, irqs_disabled(): 0, pid: 7, name: kworker/u4:0
3 locks held by kworker/u4:0/7:
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at: __write_once_size
include/linux/compiler.h:226 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at: arch_atomic64_set
arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at: atomic_long_set
include/asm-generic/atomic-long.h:40 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff888216726128 ((wq_completion)kstrp){+.+.}, at:
process_one_work+0x88b/0x1740 kernel/workqueue.c:2240
#1: ffff8880a989fdc0 ((work_completion)(&strp->work)){+.+.}, at:
process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244
#2: ffff888098998d10 (sk_lock-AF_INET){+.+.}, at: lock_sock
include/net/sock.h:1522 [inline]
#2: ffff888098998d10 (sk_lock-AF_INET){+.+.}, at: strp_sock_lock+0x2e/0x40
net/strparser/strparser.c:440
CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
01/01/2011
Workqueue: kstrp strp_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
__cant_sleep kernel/sched/core.c:6826 [inline]
__cant_sleep.cold+0xa4/0xbc kernel/sched/core.c:6803
kcm_parse_func_strparser+0x54/0x200 net/kcm/kcmsock.c:382
__strp_recv+0x5dc/0x1b20 net/strparser/strparser.c:221
strp_recv+0xcf/0x10b net/strparser/strparser.c:343
tcp_read_sock+0x285/0xa00 net/ipv4/tcp.c:1639
strp_read_sock+0x14d/0x200 net/strparser/strparser.c:366
do_strp_work net/strparser/strparser.c:414 [inline]
strp_work+0xe3/0x130 net/strparser/strparser.c:423
process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
Fixes: a2c11b034142 ("kcm: use BPF_PROG_RUN")
Fixes: 6cab5e90ab2b ("bpf: run bpf programs with preemption disabled")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: syzbot <[email protected]>
---
net/kcm/kcmsock.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index
8f12f5c6ab875ebaa6c59c6268c337919fb43bb9..ea9e73428ed9c8b7bb3441947151c41f0c099185
100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -378,8 +378,12 @@ static int kcm_parse_func_strparser(struct strparser
*strp, struct sk_buff *skb)
{
struct kcm_psock *psock = container_of(strp, struct kcm_psock, strp);
struct bpf_prog *prog = psock->bpf_prog;
+ int res;
- return BPF_PROG_RUN(prog, skb);
+ preempt_disable();
+ res = BPF_PROG_RUN(prog, skb);
+ preempt_enable();
+ return res;
}
static int kcm_read_sock_done(struct strparser *strp, int err)
--
2.23.0.351.gc4317032e6-goog
