For exposing the addresses of read/write pointers and doorbell register,
let's use the correct format specifiers. This fixes the following issues
generated using W=1 build in ARM32 and reported by Kbuild bot:
All warnings (new ones prefixed by >>):
>> drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
mhi_event->db_cfg.db_val);
^~~~~~~~~~~~~~~~~~~~~~~~
drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
mhi_chan->db_cfg.db_val);
^~~~~~~~~~~~~~~~~~~~~~~
2 warnings generated.
drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
^
drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
(u64)ring->rp, (u64)ring->wp,
^
drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
(u64)ring->rp, (u64)ring->wp,
^
drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
~~~^
%x
drivers/bus/mhi/core/debugfs.c:123:7:
mhi_chan->db_cfg.db_val);
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Manivannan Sadhasivam <[email protected]>
---
Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
branch.
drivers/bus/mhi/core/debugfs.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
index 53d05a8e168d..2536ff92b76f 100644
--- a/drivers/bus/mhi/core/debugfs.c
+++ b/drivers/bus/mhi/core/debugfs.c
@@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
er_ctxt->wp);
- seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
- mhi_event->db_cfg.db_val);
+ seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
+ &mhi_event->db_cfg.db_val);
}
return 0;
@@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
- seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
- (u64)ring->rp, (u64)ring->wp,
- mhi_chan->db_cfg.db_val);
+ seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
+ ring->rp, ring->wp,
+ &mhi_chan->db_cfg.db_val);
}
return 0;
--
2.17.1
On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> For exposing the addresses of read/write pointers and doorbell register,
> let's use the correct format specifiers. This fixes the following issues
> generated using W=1 build in ARM32 and reported by Kbuild bot:
>
> All warnings (new ones prefixed by >>):
>
>>> drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> mhi_event->db_cfg.db_val);
> ^~~~~~~~~~~~~~~~~~~~~~~~
> drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> mhi_chan->db_cfg.db_val);
> ^~~~~~~~~~~~~~~~~~~~~~~
> 2 warnings generated.
>
> drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> ^
> drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> (u64)ring->rp, (u64)ring->wp,
> ^
> drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> (u64)ring->rp, (u64)ring->wp,
> ^
> drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> ~~~^
> %x
> drivers/bus/mhi/core/debugfs.c:123:7:
> mhi_chan->db_cfg.db_val);
>
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Manivannan Sadhasivam <[email protected]>
> ---
>
> Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> branch.
>
> drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> index 53d05a8e168d..2536ff92b76f 100644
> --- a/drivers/bus/mhi/core/debugfs.c
> +++ b/drivers/bus/mhi/core/debugfs.c
> @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> er_ctxt->wp);
>
> - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> - mhi_event->db_cfg.db_val);
> + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> + &mhi_event->db_cfg.db_val);
> }
>
> return 0;
> @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
>
> - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> - (u64)ring->rp, (u64)ring->wp,
> - mhi_chan->db_cfg.db_val);
> + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> + ring->rp, ring->wp,
> + &mhi_chan->db_cfg.db_val);
> }
>
> return 0;
>
Documentation/printk-formats.txt seems to point out that %px is
"insecure" and thus perhaps not preferred. Are we assuming that debugfs
is only accessible by root, and thus the %px usage here is effectively
the same as %pK?
--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote:
> On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> > For exposing the addresses of read/write pointers and doorbell register,
> > let's use the correct format specifiers. This fixes the following issues
> > generated using W=1 build in ARM32 and reported by Kbuild bot:
> >
> > All warnings (new ones prefixed by >>):
> >
> > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > mhi_event->db_cfg.db_val);
> > ^~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > mhi_chan->db_cfg.db_val);
> > ^~~~~~~~~~~~~~~~~~~~~~~
> > 2 warnings generated.
> >
> > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> > ^
> > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > (u64)ring->rp, (u64)ring->wp,
> > ^
> > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > (u64)ring->rp, (u64)ring->wp,
> > ^
> > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > ~~~^
> > %x
> > drivers/bus/mhi/core/debugfs.c:123:7:
> > mhi_chan->db_cfg.db_val);
> >
> > Reported-by: kernel test robot <[email protected]>
> > Signed-off-by: Manivannan Sadhasivam <[email protected]>
> > ---
> >
> > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> > branch.
> >
> > drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> > index 53d05a8e168d..2536ff92b76f 100644
> > --- a/drivers/bus/mhi/core/debugfs.c
> > +++ b/drivers/bus/mhi/core/debugfs.c
> > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> > er_ctxt->wp);
> > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> > - mhi_event->db_cfg.db_val);
> > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> > + &mhi_event->db_cfg.db_val);
> > }
> > return 0;
> > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
> > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > - (u64)ring->rp, (u64)ring->wp,
> > - mhi_chan->db_cfg.db_val);
> > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> > + ring->rp, ring->wp,
> > + &mhi_chan->db_cfg.db_val);
> > }
> > return 0;
> >
>
> Documentation/printk-formats.txt seems to point out that %px is "insecure"
> and thus perhaps not preferred. Are we assuming that debugfs is only
> accessible by root, and thus the %px usage here is effectively the same as
> %pK?
>
No, this debugfs entry can be read by non-root users also. But the idea here
is to effectively show the addresses to everyone so I don't think we need to
hide it. The term "insecure" applies to kernel log where exposing the address
doesn't make much sense (except for few obvious reasons).
Thanks,
Mani
> --
> Jeffrey Hugo
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.
On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote:
> On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote:
> > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> > > For exposing the addresses of read/write pointers and doorbell register,
> > > let's use the correct format specifiers. This fixes the following issues
> > > generated using W=1 build in ARM32 and reported by Kbuild bot:
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > mhi_event->db_cfg.db_val);
> > > ^~~~~~~~~~~~~~~~~~~~~~~~
> > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > mhi_chan->db_cfg.db_val);
> > > ^~~~~~~~~~~~~~~~~~~~~~~
> > > 2 warnings generated.
> > >
> > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> > > ^
> > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > (u64)ring->rp, (u64)ring->wp,
> > > ^
> > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > (u64)ring->rp, (u64)ring->wp,
> > > ^
> > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > ~~~^
> > > %x
> > > drivers/bus/mhi/core/debugfs.c:123:7:
> > > mhi_chan->db_cfg.db_val);
> > >
> > > Reported-by: kernel test robot <[email protected]>
> > > Signed-off-by: Manivannan Sadhasivam <[email protected]>
> > > ---
> > >
> > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> > > branch.
> > >
> > > drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> > > 1 file changed, 5 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> > > index 53d05a8e168d..2536ff92b76f 100644
> > > --- a/drivers/bus/mhi/core/debugfs.c
> > > +++ b/drivers/bus/mhi/core/debugfs.c
> > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> > > er_ctxt->wp);
> > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> > > - mhi_event->db_cfg.db_val);
> > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> > > + &mhi_event->db_cfg.db_val);
> > > }
> > > return 0;
> > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
> > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > - (u64)ring->rp, (u64)ring->wp,
> > > - mhi_chan->db_cfg.db_val);
> > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> > > + ring->rp, ring->wp,
> > > + &mhi_chan->db_cfg.db_val);
> > > }
> > > return 0;
> > >
> >
> > Documentation/printk-formats.txt seems to point out that %px is "insecure"
> > and thus perhaps not preferred. Are we assuming that debugfs is only
> > accessible by root, and thus the %px usage here is effectively the same as
> > %pK?
> >
>
> No, this debugfs entry can be read by non-root users also.
How, the mount point of debugfs is restricted to root only :)
> But the idea here
> is to effectively show the addresses to everyone so I don't think we need to
> hide it. The term "insecure" applies to kernel log where exposing the address
> doesn't make much sense (except for few obvious reasons).
Why does normal users need to see a kernel address? What can they do
with this? Why can't we use the "normal" hashed way of showing a kernel
address instead?
thanks,
greg k-h
On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote:
> On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote:
> > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote:
> > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> > > > For exposing the addresses of read/write pointers and doorbell register,
> > > > let's use the correct format specifiers. This fixes the following issues
> > > > generated using W=1 build in ARM32 and reported by Kbuild bot:
> > > >
> > > > All warnings (new ones prefixed by >>):
> > > >
> > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > mhi_event->db_cfg.db_val);
> > > > ^~~~~~~~~~~~~~~~~~~~~~~~
> > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > mhi_chan->db_cfg.db_val);
> > > > ^~~~~~~~~~~~~~~~~~~~~~~
> > > > 2 warnings generated.
> > > >
> > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> > > > ^
> > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > (u64)ring->rp, (u64)ring->wp,
> > > > ^
> > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > (u64)ring->rp, (u64)ring->wp,
> > > > ^
> > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > ~~~^
> > > > %x
> > > > drivers/bus/mhi/core/debugfs.c:123:7:
> > > > mhi_chan->db_cfg.db_val);
> > > >
> > > > Reported-by: kernel test robot <[email protected]>
> > > > Signed-off-by: Manivannan Sadhasivam <[email protected]>
> > > > ---
> > > >
> > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> > > > branch.
> > > >
> > > > drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> > > > 1 file changed, 5 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> > > > index 53d05a8e168d..2536ff92b76f 100644
> > > > --- a/drivers/bus/mhi/core/debugfs.c
> > > > +++ b/drivers/bus/mhi/core/debugfs.c
> > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> > > > er_ctxt->wp);
> > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> > > > - mhi_event->db_cfg.db_val);
> > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> > > > + &mhi_event->db_cfg.db_val);
> > > > }
> > > > return 0;
> > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
> > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > - (u64)ring->rp, (u64)ring->wp,
> > > > - mhi_chan->db_cfg.db_val);
> > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> > > > + ring->rp, ring->wp,
> > > > + &mhi_chan->db_cfg.db_val);
> > > > }
> > > > return 0;
> > > >
> > >
> > > Documentation/printk-formats.txt seems to point out that %px is "insecure"
> > > and thus perhaps not preferred. Are we assuming that debugfs is only
> > > accessible by root, and thus the %px usage here is effectively the same as
> > > %pK?
> > >
> >
> > No, this debugfs entry can be read by non-root users also.
>
> How, the mount point of debugfs is restricted to root only :)
>
Sigh... I just went with the file permission of 444 :/
> > But the idea here
> > is to effectively show the addresses to everyone so I don't think we need to
> > hide it. The term "insecure" applies to kernel log where exposing the address
> > doesn't make much sense (except for few obvious reasons).
>
> Why does normal users need to see a kernel address? What can they do
> with this? Why can't we use the "normal" hashed way of showing a kernel
> address instead?
>
It was the original implementation and as you brushed my memory, only root can
mount and read the content, so why we should hide?
Thanks,
Mani
> thanks,
>
> greg k-h
On Sat, Sep 26, 2020 at 12:46:04PM +0530, Manivannan Sadhasivam wrote:
> On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote:
> > On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote:
> > > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote:
> > > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> > > > > For exposing the addresses of read/write pointers and doorbell register,
> > > > > let's use the correct format specifiers. This fixes the following issues
> > > > > generated using W=1 build in ARM32 and reported by Kbuild bot:
> > > > >
> > > > > All warnings (new ones prefixed by >>):
> > > > >
> > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > > mhi_event->db_cfg.db_val);
> > > > > ^~~~~~~~~~~~~~~~~~~~~~~~
> > > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > > mhi_chan->db_cfg.db_val);
> > > > > ^~~~~~~~~~~~~~~~~~~~~~~
> > > > > 2 warnings generated.
> > > > >
> > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> > > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> > > > > ^
> > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> > > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > (u64)ring->rp, (u64)ring->wp,
> > > > > ^
> > > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > (u64)ring->rp, (u64)ring->wp,
> > > > > ^
> > > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> > > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > > ~~~^
> > > > > %x
> > > > > drivers/bus/mhi/core/debugfs.c:123:7:
> > > > > mhi_chan->db_cfg.db_val);
> > > > >
> > > > > Reported-by: kernel test robot <[email protected]>
> > > > > Signed-off-by: Manivannan Sadhasivam <[email protected]>
> > > > > ---
> > > > >
> > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> > > > > branch.
> > > > >
> > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> > > > > 1 file changed, 5 insertions(+), 5 deletions(-)
> > > > >
> > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> > > > > index 53d05a8e168d..2536ff92b76f 100644
> > > > > --- a/drivers/bus/mhi/core/debugfs.c
> > > > > +++ b/drivers/bus/mhi/core/debugfs.c
> > > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> > > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> > > > > er_ctxt->wp);
> > > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> > > > > - mhi_event->db_cfg.db_val);
> > > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> > > > > + &mhi_event->db_cfg.db_val);
> > > > > }
> > > > > return 0;
> > > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> > > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> > > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
> > > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > > - (u64)ring->rp, (u64)ring->wp,
> > > > > - mhi_chan->db_cfg.db_val);
> > > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> > > > > + ring->rp, ring->wp,
> > > > > + &mhi_chan->db_cfg.db_val);
> > > > > }
> > > > > return 0;
> > > > >
> > > >
> > > > Documentation/printk-formats.txt seems to point out that %px is "insecure"
> > > > and thus perhaps not preferred. Are we assuming that debugfs is only
> > > > accessible by root, and thus the %px usage here is effectively the same as
> > > > %pK?
> > > >
> > >
> > > No, this debugfs entry can be read by non-root users also.
> >
> > How, the mount point of debugfs is restricted to root only :)
> >
>
> Sigh... I just went with the file permission of 444 :/
>
> > > But the idea here
> > > is to effectively show the addresses to everyone so I don't think we need to
> > > hide it. The term "insecure" applies to kernel log where exposing the address
> > > doesn't make much sense (except for few obvious reasons).
> >
> > Why does normal users need to see a kernel address? What can they do
> > with this? Why can't we use the "normal" hashed way of showing a kernel
> > address instead?
> >
>
> It was the original implementation and as you brushed my memory, only root can
> mount and read the content, so why we should hide?
Why shouldn't you? It's good to have defense in depth, userspace should
not care about a real kernel pointer value, right? THat's why we have
the hashed number instead, please use that.
thanks,
greg k-h
On Sat, Sep 26, 2020 at 02:46:26PM +0200, Greg KH wrote:
> On Sat, Sep 26, 2020 at 12:46:04PM +0530, Manivannan Sadhasivam wrote:
> > On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote:
> > > On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote:
> > > > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote:
> > > > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote:
> > > > > > For exposing the addresses of read/write pointers and doorbell register,
> > > > > > let's use the correct format specifiers. This fixes the following issues
> > > > > > generated using W=1 build in ARM32 and reported by Kbuild bot:
> > > > > >
> > > > > > All warnings (new ones prefixed by >>):
> > > > > >
> > > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > > > mhi_event->db_cfg.db_val);
> > > > > > ^~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat]
> > > > > > mhi_chan->db_cfg.db_val);
> > > > > > ^~~~~~~~~~~~~~~~~~~~~~~
> > > > > > 2 warnings generated.
> > > > > >
> > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’:
> > > > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp,
> > > > > > ^
> > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’:
> > > > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > > (u64)ring->rp, (u64)ring->wp,
> > > > > > ^
> > > > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> > > > > > (u64)ring->rp, (u64)ring->wp,
> > > > > > ^
> > > > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=]
> > > > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > > > ~~~^
> > > > > > %x
> > > > > > drivers/bus/mhi/core/debugfs.c:123:7:
> > > > > > mhi_chan->db_cfg.db_val);
> > > > > >
> > > > > > Reported-by: kernel test robot <[email protected]>
> > > > > > Signed-off-by: Manivannan Sadhasivam <[email protected]>
> > > > > > ---
> > > > > >
> > > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing
> > > > > > branch.
> > > > > >
> > > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++-----
> > > > > > 1 file changed, 5 insertions(+), 5 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
> > > > > > index 53d05a8e168d..2536ff92b76f 100644
> > > > > > --- a/drivers/bus/mhi/core/debugfs.c
> > > > > > +++ b/drivers/bus/mhi/core/debugfs.c
> > > > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d)
> > > > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp,
> > > > > > er_ctxt->wp);
> > > > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp,
> > > > > > - mhi_event->db_cfg.db_val);
> > > > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp,
> > > > > > + &mhi_event->db_cfg.db_val);
> > > > > > }
> > > > > > return 0;
> > > > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
> > > > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx",
> > > > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
> > > > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n",
> > > > > > - (u64)ring->rp, (u64)ring->wp,
> > > > > > - mhi_chan->db_cfg.db_val);
> > > > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n",
> > > > > > + ring->rp, ring->wp,
> > > > > > + &mhi_chan->db_cfg.db_val);
> > > > > > }
> > > > > > return 0;
> > > > > >
> > > > >
> > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure"
> > > > > and thus perhaps not preferred. Are we assuming that debugfs is only
> > > > > accessible by root, and thus the %px usage here is effectively the same as
> > > > > %pK?
> > > > >
> > > >
> > > > No, this debugfs entry can be read by non-root users also.
> > >
> > > How, the mount point of debugfs is restricted to root only :)
> > >
> >
> > Sigh... I just went with the file permission of 444 :/
> >
> > > > But the idea here
> > > > is to effectively show the addresses to everyone so I don't think we need to
> > > > hide it. The term "insecure" applies to kernel log where exposing the address
> > > > doesn't make much sense (except for few obvious reasons).
> > >
> > > Why does normal users need to see a kernel address? What can they do
> > > with this? Why can't we use the "normal" hashed way of showing a kernel
> > > address instead?
> > >
> >
> > It was the original implementation and as you brushed my memory, only root can
> > mount and read the content, so why we should hide?
>
> Why shouldn't you? It's good to have defense in depth, userspace should
> not care about a real kernel pointer value, right? THat's why we have
> the hashed number instead, please use that.
>
Okay. Will do it in next revision.
Thanks,
Mani
> thanks,
>
> greg k-h