4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit af3fb24eecb2c59246e03c99386037fd5ad84ffd ]
Since tun->flags might be shared by multiple tfile structures, it is better to make sure tun_get_user() is using the flags for the current tfile.
Presence of the READ_ONCE() in tun_napi_frags_enabled() gave a hint of what could happen, but we need something stronger to please syzbot.
kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 13647 Comm: syz-executor5 Not tainted 4.19.0-rc5+ #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:dev_gro_receive+0x132/0x2720 net/core/dev.c:5427 Code: 48 c1 ea 03 80 3c 02 00 0f 85 6e 20 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 6e 10 49 8d bd d0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 59 20 00 00 4d 8b a5 d0 00 00 00 31 ff 41 81 e4 RSP: 0018:ffff8801c400f410 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8618d325 RDX: 000000000000001a RSI: ffffffff86189f97 RDI: 00000000000000d0 RBP: ffff8801c400f608 R08: ffff8801c8fb4300 R09: 0000000000000000 R10: ffffed0038801ed7 R11: 0000000000000003 R12: ffff8801d327d358 R13: 0000000000000000 R14: ffff8801c16dd8c0 R15: 0000000000000004 FS: 00007fe003615700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe1f3c43db8 CR3: 00000001bebb2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: napi_gro_frags+0x3f4/0xc90 net/core/dev.c:5715 tun_get_user+0x31d5/0x42a0 drivers/net/tun.c:1922 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1967 call_write_iter include/linux/fs.h:1808 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x6b8/0x9f0 fs/read_write.c:487 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457579 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe003614c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579 RDX: 0000000000000012 RSI: 0000000020000000 RDI: 000000000000000a RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe0036156d4 R13: 00000000004c5574 R14: 00000000004d8e98 R15: 00000000ffffffff Modules linked in:
RIP: 0010:dev_gro_receive+0x132/0x2720 net/core/dev.c:5427 Code: 48 c1 ea 03 80 3c 02 00 0f 85 6e 20 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 6e 10 49 8d bd d0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 59 20 00 00 4d 8b a5 d0 00 00 00 31 ff 41 81 e4 RSP: 0018:ffff8801c400f410 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8618d325 RDX: 000000000000001a RSI: ffffffff86189f97 RDI: 00000000000000d0 RBP: ffff8801c400f608 R08: ffff8801c8fb4300 R09: 0000000000000000 R10: ffffed0038801ed7 R11: 0000000000000003 R12: ffff8801d327d358 R13: 0000000000000000 R14: ffff8801c16dd8c0 R15: 0000000000000004 FS: 00007fe003615700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe1f3c43db8 CR3: 00000001bebb2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/tun.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-)
--- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -181,6 +181,7 @@ struct tun_file { }; struct napi_struct napi; bool napi_enabled; + bool napi_frags_enabled; struct mutex napi_mutex; /* Protects access to the above napi */ struct list_head next; struct tun_struct *detached; @@ -312,9 +313,10 @@ static int tun_napi_poll(struct napi_str }
static void tun_napi_init(struct tun_struct *tun, struct tun_file *tfile, - bool napi_en) + bool napi_en, bool napi_frags) { tfile->napi_enabled = napi_en; + tfile->napi_frags_enabled = napi_en && napi_frags; if (napi_en) { netif_napi_add(tun->dev, &tfile->napi, tun_napi_poll, NAPI_POLL_WEIGHT); @@ -334,9 +336,9 @@ static void tun_napi_del(struct tun_file netif_napi_del(&tfile->napi); }
-static bool tun_napi_frags_enabled(const struct tun_struct *tun) +static bool tun_napi_frags_enabled(const struct tun_file *tfile) { - return READ_ONCE(tun->flags) & IFF_NAPI_FRAGS; + return tfile->napi_frags_enabled; }
#ifdef CONFIG_TUN_VNET_CROSS_LE @@ -790,7 +792,7 @@ static void tun_detach_all(struct net_de }
static int tun_attach(struct tun_struct *tun, struct file *file, - bool skip_filter, bool napi) + bool skip_filter, bool napi, bool napi_frags) { struct tun_file *tfile = file->private_data; struct net_device *dev = tun->dev; @@ -863,7 +865,7 @@ static int tun_attach(struct tun_struct tun_enable_queue(tfile); } else { sock_hold(&tfile->sk); - tun_napi_init(tun, tfile, napi); + tun_napi_init(tun, tfile, napi, napi_frags); }
tun_set_real_num_queues(tun); @@ -1173,13 +1175,11 @@ static void tun_poll_controller(struct n struct tun_file *tfile; int i;
- if (tun_napi_frags_enabled(tun)) - return; - rcu_read_lock(); for (i = 0; i < tun->numqueues; i++) { tfile = rcu_dereference(tun->tfiles[i]); - if (tfile->napi_enabled) + if (!tun_napi_frags_enabled(tfile) && + tfile->napi_enabled) napi_schedule(&tfile->napi); } rcu_read_unlock(); @@ -1750,7 +1750,7 @@ static ssize_t tun_get_user(struct tun_s int err; u32 rxhash = 0; int skb_xdp = 1; - bool frags = tun_napi_frags_enabled(tun); + bool frags = tun_napi_frags_enabled(tfile);
if (!(tun->dev->flags & IFF_UP)) return -EIO; @@ -2575,7 +2575,8 @@ static int tun_set_iff(struct net *net, return err;
err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER, - ifr->ifr_flags & IFF_NAPI); + ifr->ifr_flags & IFF_NAPI, + ifr->ifr_flags & IFF_NAPI_FRAGS); if (err < 0) return err;
@@ -2673,7 +2674,8 @@ static int tun_set_iff(struct net *net, (ifr->ifr_flags & TUN_FEATURES);
INIT_LIST_HEAD(&tun->disabled); - err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI); + err = tun_attach(tun, file, false, ifr->ifr_flags & IFF_NAPI, + ifr->ifr_flags & IFF_NAPI_FRAGS); if (err < 0) goto err_free_flow;
@@ -2822,7 +2824,8 @@ static int tun_set_queue(struct file *fi ret = security_tun_dev_attach_queue(tun->security); if (ret < 0) goto unlock; - ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI); + ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI, + tun->flags & IFF_NAPI_FRAGS); } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) { tun = rtnl_dereference(tfile->tun); if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)