From: Yun Lu Date: Fri, 16 Jan 2026 09:53:08 +0000 (+0800) Subject: netdevsim: fix a race issue related to the operation on bpf_bound_progs list X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b97d5eedf4976cc94321243be83b39efe81a0e15;p=thirdparty%2Fkernel%2Flinux.git netdevsim: fix a race issue related to the operation on bpf_bound_progs list The netdevsim driver lacks a protection mechanism for operations on the bpf_bound_progs list. When the nsim_bpf_create_prog() performs list_add_tail, it is possible that nsim_bpf_destroy_prog() is simultaneously performs list_del. Concurrent operations on the list may lead to list corruption and trigger a kernel crash as follows: [ 417.290971] kernel BUG at lib/list_debug.c:62! [ 417.290983] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 417.290992] CPU: 10 PID: 168 Comm: kworker/10:1 Kdump: loaded Not tainted 6.19.0-rc5 #1 [ 417.291003] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 417.291007] Workqueue: events bpf_prog_free_deferred [ 417.291021] RIP: 0010:__list_del_entry_valid_or_report+0xa7/0xc0 [ 417.291034] Code: a8 ff 0f 0b 48 89 fe 48 89 ca 48 c7 c7 48 a1 eb ae e8 ed fb a8 ff 0f 0b 48 89 fe 48 89 c2 48 c7 c7 80 a1 eb ae e8 d9 fb a8 ff <0f> 0b 48 89 d1 48 c7 c7 d0 a1 eb ae 48 89 f2 48 89 c6 e8 c2 fb a8 [ 417.291040] RSP: 0018:ffffb16a40807df8 EFLAGS: 00010246 [ 417.291046] RAX: 000000000000006d RBX: ffff8e589866f500 RCX: 0000000000000000 [ 417.291051] RDX: 0000000000000000 RSI: ffff8e59f7b23180 RDI: ffff8e59f7b23180 [ 417.291055] RBP: ffffb16a412c9000 R08: 0000000000000000 R09: 0000000000000003 [ 417.291059] R10: ffffb16a40807c80 R11: ffffffffaf9edce8 R12: ffff8e594427ac20 [ 417.291063] R13: ffff8e59f7b44780 R14: ffff8e58800b7a05 R15: 0000000000000000 [ 417.291074] FS: 0000000000000000(0000) GS:ffff8e59f7b00000(0000) knlGS:0000000000000000 [ 417.291079] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 417.291083] CR2: 00007fc4083efe08 CR3: 00000001c3626006 CR4: 0000000000770ee0 [ 417.291088] PKRU: 55555554 [ 417.291091] Call Trace: [ 417.291096] [ 417.291103] nsim_bpf_destroy_prog+0x31/0x80 [netdevsim] [ 417.291154] __bpf_prog_offload_destroy+0x2a/0x80 [ 417.291163] bpf_prog_dev_bound_destroy+0x6f/0xb0 [ 417.291171] bpf_prog_free_deferred+0x18e/0x1a0 [ 417.291178] process_one_work+0x18a/0x3a0 [ 417.291188] worker_thread+0x27b/0x3a0 [ 417.291197] ? __pfx_worker_thread+0x10/0x10 [ 417.291207] kthread+0xe5/0x120 [ 417.291214] ? __pfx_kthread+0x10/0x10 [ 417.291221] ret_from_fork+0x31/0x50 [ 417.291230] ? __pfx_kthread+0x10/0x10 [ 417.291236] ret_from_fork_asm+0x1a/0x30 [ 417.291246] Add a mutex lock, to prevent simultaneous addition and deletion operations on the list. Fixes: 31d3ad832948 ("netdevsim: add bpf offload support") Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Signed-off-by: Yun Lu Link: https://patch.msgid.link/20260116095308.11441-1-luyun_611@163.com Signed-off-by: Paolo Abeni --- diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c index 49537d3c4120..5f17f68f3c08 100644 --- a/drivers/net/netdevsim/bpf.c +++ b/drivers/net/netdevsim/bpf.c @@ -244,7 +244,9 @@ static int nsim_bpf_create_prog(struct nsim_dev *nsim_dev, &state->state, &nsim_bpf_string_fops); debugfs_create_bool("loaded", 0400, state->ddir, &state->is_loaded); + mutex_lock(&nsim_dev->progs_list_lock); list_add_tail(&state->l, &nsim_dev->bpf_bound_progs); + mutex_unlock(&nsim_dev->progs_list_lock); prog->aux->offload->dev_priv = state; @@ -273,12 +275,16 @@ static int nsim_bpf_translate(struct bpf_prog *prog) static void nsim_bpf_destroy_prog(struct bpf_prog *prog) { struct nsim_bpf_bound_prog *state; + struct nsim_dev *nsim_dev; state = prog->aux->offload->dev_priv; + nsim_dev = state->nsim_dev; WARN(state->is_loaded, "offload state destroyed while program still bound"); debugfs_remove_recursive(state->ddir); + mutex_lock(&nsim_dev->progs_list_lock); list_del(&state->l); + mutex_unlock(&nsim_dev->progs_list_lock); kfree(state); } diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c index 2683a989873e..dfd571b22107 100644 --- a/drivers/net/netdevsim/dev.c +++ b/drivers/net/netdevsim/dev.c @@ -1647,6 +1647,7 @@ int nsim_drv_probe(struct nsim_bus_dev *nsim_bus_dev) nsim_dev->test1 = NSIM_DEV_TEST1_DEFAULT; nsim_dev->test2 = NSIM_DEV_TEST2_DEFAULT; spin_lock_init(&nsim_dev->fa_cookie_lock); + mutex_init(&nsim_dev->progs_list_lock); dev_set_drvdata(&nsim_bus_dev->dev, nsim_dev); @@ -1785,6 +1786,7 @@ void nsim_drv_remove(struct nsim_bus_dev *nsim_bus_dev) devl_unregister(devlink); kfree(nsim_dev->vfconfigs); kfree(nsim_dev->fa_cookie); + mutex_destroy(&nsim_dev->progs_list_lock); devl_unlock(devlink); devlink_free(devlink); dev_set_drvdata(&nsim_bus_dev->dev, NULL); diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h index d1a941e2b18f..46c67983c517 100644 --- a/drivers/net/netdevsim/netdevsim.h +++ b/drivers/net/netdevsim/netdevsim.h @@ -324,6 +324,7 @@ struct nsim_dev { u32 prog_id_gen; struct list_head bpf_bound_progs; struct list_head bpf_bound_maps; + struct mutex progs_list_lock; struct netdev_phys_item_id switch_id; struct list_head port_list; bool fw_update_status;