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authorEric Dumazet <edumazet@google.com>2019-05-13 09:38:55 -0700
committerDavid S. Miller <davem@davemloft.net>2019-05-13 09:53:42 -0700
commitb1c17a9a353878602fd5bfe9103e4afe5e9a3f96 (patch)
tree51800af84a98c97588f278596b769523976e53d0 /net/core/flow_dissector.c
parentbonding: fix arp_validate toggling in active-backup mode (diff)
downloadlinux-dev-b1c17a9a353878602fd5bfe9103e4afe5e9a3f96.tar.xz
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flow_dissector: disable preemption around BPF calls
Various things in eBPF really require us to disable preemption before running an eBPF program. syzbot reported : BUG: assuming atomic context at net/core/flow_dissector.c:737 in_atomic(): 0, irqs_disabled(): 0, pid: 24710, name: syz-executor.3 2 locks held by syz-executor.3/24710: #0: 00000000e81a4bf1 (&tfile->napi_mutex){+.+.}, at: tun_get_user+0x168e/0x3ff0 drivers/net/tun.c:1850 #1: 00000000254afebd (rcu_read_lock){....}, at: __skb_flow_dissect+0x1e1/0x4bb0 net/core/flow_dissector.c:822 CPU: 1 PID: 24710 Comm: syz-executor.3 Not tainted 5.1.0+ #6 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 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:6165 [inline] __cant_sleep.cold+0xa3/0xbb kernel/sched/core.c:6142 bpf_flow_dissect+0xfe/0x390 net/core/flow_dissector.c:737 __skb_flow_dissect+0x362/0x4bb0 net/core/flow_dissector.c:853 skb_flow_dissect_flow_keys_basic include/linux/skbuff.h:1322 [inline] skb_probe_transport_header include/linux/skbuff.h:2500 [inline] skb_probe_transport_header include/linux/skbuff.h:2493 [inline] tun_get_user+0x2cfe/0x3ff0 drivers/net/tun.c:1940 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2037 call_write_iter include/linux/fs.h:1872 [inline] do_iter_readv_writev+0x5fd/0x900 fs/read_write.c:693 do_iter_write fs/read_write.c:970 [inline] do_iter_write+0x184/0x610 fs/read_write.c:951 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015 do_writev+0x15b/0x330 fs/read_write.c:1058 __do_sys_writev fs/read_write.c:1131 [inline] __se_sys_writev fs/read_write.c:1128 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: Petar Penkov <ppenkov@google.com> Cc: Stanislav Fomichev <sdf@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/flow_dissector.c')
-rw-r--r--net/core/flow_dissector.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 9ca784c592ac..548f39dde307 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -734,7 +734,9 @@ bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx,
flow_keys->nhoff = nhoff;
flow_keys->thoff = flow_keys->nhoff;
+ preempt_disable();
result = BPF_PROG_RUN(prog, ctx);
+ preempt_enable();
flow_keys->nhoff = clamp_t(u16, flow_keys->nhoff, nhoff, hlen);
flow_keys->thoff = clamp_t(u16, flow_keys->thoff,