| Message ID | 20200730160900.187157-1-hch@lst.de |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [net] net/bpfilter: initialize pos in __bpfilter_process_sockopt | expand |
On Thu, Jul 30, 2020 at 06:09:00PM +0200, Christoph Hellwig wrote: > __bpfilter_process_sockopt never initialized the pos variable passed to > the pipe write. This has been mostly harmless in the past as pipes > ignore the offset, but the switch to kernel_write no verified the s/no/now/ > position, which can lead to a failure depending on the exact stack > initialization patter. Initialize the variable to zero to make s/patter/pattern/ > rw_verify_area happy. > > Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write") > Reported-by: Christian Brauner <christian.brauner@ubuntu.com> > Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com> > Signed-off-by: Christoph Hellwig <hch@lst.de> > Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com> > --- Thanks for tracking this down, Christoph! This fixes the logging issue for me. Tested-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> > net/bpfilter/bpfilter_kern.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c > index 1905e01c3aa9a7..4494ea6056cdb8 100644 > --- a/net/bpfilter/bpfilter_kern.c > +++ b/net/bpfilter/bpfilter_kern.c > @@ -39,7 +39,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, > { > struct mbox_request req; > struct mbox_reply reply; > - loff_t pos; > + loff_t pos = 0; > ssize_t n; > int ret = -EFAULT; > > -- > 2.27.0 >
On 7/30/20 6:13 PM, Christian Brauner wrote: > On Thu, Jul 30, 2020 at 06:09:00PM +0200, Christoph Hellwig wrote: >> __bpfilter_process_sockopt never initialized the pos variable passed to >> the pipe write. This has been mostly harmless in the past as pipes >> ignore the offset, but the switch to kernel_write no verified the > > s/no/now/ > >> position, which can lead to a failure depending on the exact stack >> initialization patter. Initialize the variable to zero to make > > s/patter/pattern/ > >> rw_verify_area happy. >> >> Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write") >> Reported-by: Christian Brauner <christian.brauner@ubuntu.com> >> Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com> >> Signed-off-by: Christoph Hellwig <hch@lst.de> >> Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com> >> --- > > Thanks for tracking this down, Christoph! This fixes the logging issue > for me. > Tested-by: Christian Brauner <christian.brauner@ubuntu.com> > Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> Applied to bpf & fixed up the typos in the commit msg, thanks everyone!
On Fri, Jul 31, 2020 at 02:07:42AM +0200, Daniel Borkmann wrote: > On 7/30/20 6:13 PM, Christian Brauner wrote: > > On Thu, Jul 30, 2020 at 06:09:00PM +0200, Christoph Hellwig wrote: > > > __bpfilter_process_sockopt never initialized the pos variable passed to > > > the pipe write. This has been mostly harmless in the past as pipes > > > ignore the offset, but the switch to kernel_write no verified the > > > > s/no/now/ > > > > > position, which can lead to a failure depending on the exact stack > > > initialization patter. Initialize the variable to zero to make > > > > s/patter/pattern/ > > > > > rw_verify_area happy. > > > > > > Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write") > > > Reported-by: Christian Brauner <christian.brauner@ubuntu.com> > > > Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com> > > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > > Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com> > > > --- > > > > Thanks for tracking this down, Christoph! This fixes the logging issue > > for me. > > Tested-by: Christian Brauner <christian.brauner@ubuntu.com> > > Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> > > Applied to bpf & fixed up the typos in the commit msg, thanks everyone! Daniel, why is it necessary in bpf tree? I fixed it already in bpf-next in commit a4fa458950b4 ("bpfilter: Initialize pos variable") two weeks ago...
On 8/1/20 9:48 PM, Alexei Starovoitov wrote: > On Fri, Jul 31, 2020 at 02:07:42AM +0200, Daniel Borkmann wrote: >> On 7/30/20 6:13 PM, Christian Brauner wrote: >>> On Thu, Jul 30, 2020 at 06:09:00PM +0200, Christoph Hellwig wrote: >>>> __bpfilter_process_sockopt never initialized the pos variable passed to >>>> the pipe write. This has been mostly harmless in the past as pipes >>>> ignore the offset, but the switch to kernel_write no verified the >>> >>> s/no/now/ >>> >>>> position, which can lead to a failure depending on the exact stack >>>> initialization patter. Initialize the variable to zero to make >>> >>> s/patter/pattern/ >>> >>>> rw_verify_area happy. >>>> >>>> Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write") >>>> Reported-by: Christian Brauner <christian.brauner@ubuntu.com> >>>> Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com> >>>> Signed-off-by: Christoph Hellwig <hch@lst.de> >>>> Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com> >>>> --- >>> >>> Thanks for tracking this down, Christoph! This fixes the logging issue >>> for me. >>> Tested-by: Christian Brauner <christian.brauner@ubuntu.com> >>> Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> >> >> Applied to bpf & fixed up the typos in the commit msg, thanks everyone! > > Daniel, > why is it necessary in bpf tree? > > I fixed it already in bpf-next in commit a4fa458950b4 ("bpfilter: Initialize pos variable") > two weeks ago... Several folks reported that with v5.8-rc kernels their console is spammed with 'bpfilter: write fail' messages [0]. Given this affected the 5.8 release and the fix was a one-line change, it felt appropriate to route it there. Why was a4fa458950b4 not pushed into bpf tree given it was affected there too? Either way, we can undo the double pos assignment upon tree sync.. [0] https://lore.kernel.org/lkml/20200727104636.nuz3u4xb7ba7ue5a@wittgenstein/
On Mon, Aug 03, 2020 at 04:56:35PM +0200, Daniel Borkmann wrote: > On 8/1/20 9:48 PM, Alexei Starovoitov wrote: > > Several folks reported that with v5.8-rc kernels their console is spammed with > 'bpfilter: write fail' messages [0]. Given this affected the 5.8 release and > the fix was a one-line change, it felt appropriate to route it there. Why was > a4fa458950b4 not pushed into bpf tree given it was affected there too? Either > way, we can undo the double pos assignment upon tree sync.. Just as a side note, please note it was more than spamming on the console. It prevented the subsystem from working at all. Best regards, Madera
diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index 1905e01c3aa9a7..4494ea6056cdb8 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -39,7 +39,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, { struct mbox_request req; struct mbox_reply reply; - loff_t pos; + loff_t pos = 0; ssize_t n; int ret = -EFAULT;
__bpfilter_process_sockopt never initialized the pos variable passed to the pipe write. This has been mostly harmless in the past as pipes ignore the offset, but the switch to kernel_write no verified the position, which can lead to a failure depending on the exact stack initialization patter. Initialize the variable to zero to make rw_verify_area happy. Fixes: 6955a76fbcd5 ("bpfilter: switch to kernel_write") Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Reported-by: Rodrigo Madera <rodrigo.madera@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Rodrigo Madera <rodrigo.madera@gmail.com> --- net/bpfilter/bpfilter_kern.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)