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Subject[PATCH 4.14 061/165] bpf: use GFP_ATOMIC instead of GFP_KERNEL in bpf_parse_prog()
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit 71eb5255f55bdb484d35ff7c9a1803f453dfbf82 ]

bpf_parse_prog() is protected by rcu_read_lock().
so that GFP_KERNEL is not allowed in the bpf_parse_prog().

[51015.579396] =============================
[51015.579418] WARNING: suspicious RCU usage
[51015.579444] 4.18.0-rc6+ #208 Not tainted
[51015.579464] -----------------------------
[51015.579488] ./include/linux/rcupdate.h:303 Illegal context switch in RCU read-side critical section!
[51015.579510] other info that might help us debug this:
[51015.579532] rcu_scheduler_active = 2, debug_locks = 1
[51015.579556] 2 locks held by ip/1861:
[51015.579577] #0: 00000000a8c12fd1 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x2e0/0x910
[51015.579711] #1: 00000000bf815f8e (rcu_read_lock){....}, at: lwtunnel_build_state+0x96/0x390
[51015.579842] stack backtrace:
[51015.579869] CPU: 0 PID: 1861 Comm: ip Not tainted 4.18.0-rc6+ #208
[51015.579891] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
[51015.579911] Call Trace:
[51015.579950] dump_stack+0x74/0xbb
[51015.580000] ___might_sleep+0x16b/0x3a0
[51015.580047] __kmalloc_track_caller+0x220/0x380
[51015.580077] kmemdup+0x1c/0x40
[51015.580077] bpf_parse_prog+0x10e/0x230
[51015.580164] ? kasan_kmalloc+0xa0/0xd0
[51015.580164] ? bpf_destroy_state+0x30/0x30
[51015.580164] ? bpf_build_state+0xe2/0x3e0
[51015.580164] bpf_build_state+0x1bb/0x3e0
[51015.580164] ? bpf_parse_prog+0x230/0x230
[51015.580164] ? lock_is_held_type+0x123/0x1a0
[51015.580164] lwtunnel_build_state+0x1aa/0x390
[51015.580164] fib_create_info+0x1579/0x33d0
[51015.580164] ? sched_clock_local+0xe2/0x150
[51015.580164] ? fib_info_update_nh_saddr+0x1f0/0x1f0
[51015.580164] ? sched_clock_local+0xe2/0x150
[51015.580164] fib_table_insert+0x201/0x1990
[51015.580164] ? lock_downgrade+0x610/0x610
[51015.580164] ? fib_table_lookup+0x1920/0x1920
[51015.580164] ? lwtunnel_valid_encap_type.part.6+0xcb/0x3a0
[51015.580164] ? rtm_to_fib_config+0x637/0xbd0
[51015.580164] inet_rtm_newroute+0xed/0x1b0
[51015.580164] ? rtm_to_fib_config+0xbd0/0xbd0
[51015.580164] rtnetlink_rcv_msg+0x331/0x910
[ ... ]

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/lwt_bpf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -217,7 +217,7 @@ static int bpf_parse_prog(struct nlattr
if (!tb[LWT_BPF_PROG_FD] || !tb[LWT_BPF_PROG_NAME])
return -EINVAL;

- prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_KERNEL);
+ prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_ATOMIC);
if (!prog->name)
return -ENOMEM;


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