4.18-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit c7256f579f8302ce2c038181c30060d0b40017b2 ]
This is the first part to fix following syzbot report :
console output: https://syzkaller.appspot.com/x/log.txt?x=145378e6400000 kernel config: https://syzkaller.appspot.com/x/.config?x=443816db871edd66 dashboard link: https://syzkaller.appspot.com/bug?extid=e662df0ac1d753b57e80
Following patch is fixing the race condition, but it seems safer to initialize this mutex at tfile creation anyway.
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot+e662df0ac1d753b57e80@syzkaller.appspotmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -319,7 +319,6 @@ static void tun_napi_init(struct tun_str netif_napi_add(tun->dev, &tfile->napi, tun_napi_poll, NAPI_POLL_WEIGHT); napi_enable(&tfile->napi); - mutex_init(&tfile->napi_mutex); } }
@@ -3241,6 +3240,7 @@ static int tun_chr_open(struct inode *in return -ENOMEM; }
+ mutex_init(&tfile->napi_mutex); RCU_INIT_POINTER(tfile->tun, NULL); tfile->flags = 0; tfile->ifindex = 0;