There are three changes but none of them should affect run time:
1) You can't write to this file because the permissions are 0444. But
it sort of looked like you could do a write and it would result in
a read. Then it looked like proc_sys_call_handler() just ignored
it. Which is confusing. It's more clear if the "write" just
returns zero.
2) The "lenp" pointer is never NULL so that check can be removed.
3) In the original code, the "if (*lenp < 0)" check didn't work because
"*lenp" is unsigned. Fortunately, the memory_read_from_buffer()
call will never fail in this context so it doesn't affect runtime.
Signed-off-by: Dan Carpenter <[email protected]>
---
net/sunrpc/sysctl.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index a18b36b5422d..04526bab4a06 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -63,19 +63,19 @@ static int proc_do_xprt(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[256];
- size_t len;
+ ssize_t len;
- if ((*ppos && !write) || !*lenp) {
- *lenp = 0;
+ *lenp = 0;
+
+ if (write || *ppos)
return 0;
- }
+
len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
- *lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
+ len = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
+ if (len < 0)
+ return len;
- if (*lenp < 0) {
- *lenp = 0;
- return -EINVAL;
- }
+ *lenp = len;
return 0;
}
--
2.28.0
On Tue, Oct 27, 2020 at 05:17:58PM +0300, Dan Carpenter wrote:
> There are three changes but none of them should affect run time:
>
> 1) You can't write to this file because the permissions are 0444. But
> it sort of looked like you could do a write and it would result in
> a read. Then it looked like proc_sys_call_handler() just ignored
> it. Which is confusing. It's more clear if the "write" just
> returns zero.
> 2) The "lenp" pointer is never NULL so that check can be removed.
> 3) In the original code, the "if (*lenp < 0)" check didn't work because
> "*lenp" is unsigned. Fortunately, the memory_read_from_buffer()
> call will never fail in this context so it doesn't affect runtime.
>
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> net/sunrpc/sysctl.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
> index a18b36b5422d..04526bab4a06 100644
> --- a/net/sunrpc/sysctl.c
> +++ b/net/sunrpc/sysctl.c
> @@ -63,19 +63,19 @@ static int proc_do_xprt(struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> char tmpbuf[256];
> - size_t len;
> + ssize_t len;
>
> - if ((*ppos && !write) || !*lenp) {
> - *lenp = 0;
> + *lenp = 0;
> +
> + if (write || *ppos)
> return 0;
> - }
> +
> len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
> - *lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
> + len = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
Except now we're passing *lenp = 0, that can't be right.
Though I actually kind of prefer this to Colin King's patch which just
casts (*lenp) in the comparison below.
--b.
> + if (len < 0)
> + return len;
>
> - if (*lenp < 0) {
> - *lenp = 0;
> - return -EINVAL;
> - }
> + *lenp = len;
> return 0;
> }
>
> --
> 2.28.0
On Fri, Nov 06, 2020 at 03:33:16PM -0500, J. Bruce Fields wrote:
> On Tue, Oct 27, 2020 at 05:17:58PM +0300, Dan Carpenter wrote:
> > There are three changes but none of them should affect run time:
> >
> > 1) You can't write to this file because the permissions are 0444. But
> > it sort of looked like you could do a write and it would result in
> > a read. Then it looked like proc_sys_call_handler() just ignored
> > it. Which is confusing. It's more clear if the "write" just
> > returns zero.
> > 2) The "lenp" pointer is never NULL so that check can be removed.
> > 3) In the original code, the "if (*lenp < 0)" check didn't work because
> > "*lenp" is unsigned. Fortunately, the memory_read_from_buffer()
> > call will never fail in this context so it doesn't affect runtime.
> >
> > Signed-off-by: Dan Carpenter <[email protected]>
> > ---
> > net/sunrpc/sysctl.c | 18 +++++++++---------
> > 1 file changed, 9 insertions(+), 9 deletions(-)
> >
> > diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
> > index a18b36b5422d..04526bab4a06 100644
> > --- a/net/sunrpc/sysctl.c
> > +++ b/net/sunrpc/sysctl.c
> > @@ -63,19 +63,19 @@ static int proc_do_xprt(struct ctl_table *table, int write,
> > void *buffer, size_t *lenp, loff_t *ppos)
> > {
> > char tmpbuf[256];
> > - size_t len;
> > + ssize_t len;
> >
> > - if ((*ppos && !write) || !*lenp) {
> > - *lenp = 0;
> > + *lenp = 0;
> > +
> > + if (write || *ppos)
> > return 0;
> > - }
> > +
> > len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
> > - *lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
> > + len = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
>
> Except now we're passing *lenp = 0, that can't be right.
>
> Though I actually kind of prefer this to Colin King's patch which just
> casts (*lenp) in the comparison below.
So, maybe just leave all the ugly *lenp = 0's and otherwise keep your
version:
commit d435c05ab019
Author: Dan Carpenter <[email protected]>
Date: Fri Nov 6 15:39:50 2020 -0500
net/sunrpc: return 0 on attempt to write to "transports"
You can't write to this file because the permissions are 0444. But
it sort of looked like you could do a write and it would result in
a read. Then it looked like proc_sys_call_handler() just ignored
it. Which is confusing. It's more clear if the "write" just
returns zero.
Also, the "lenp" pointer is never NULL so that check can be removed.
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: J. Bruce Fields <[email protected]>
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index a18b36b5422d..5c9f5bca4d99 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -65,7 +65,7 @@ static int proc_do_xprt(struct ctl_table *table, int write,
char tmpbuf[256];
size_t len;
- if ((*ppos && !write) || !*lenp) {
+ if (write || *ppos) {
*lenp = 0;
return 0;
}
commit bfb5aa1685d5
Author: Dan Carpenter <[email protected]>
Date: Fri Nov 6 15:50:39 2020 -0500
net/sunrpc: fix useless comparison in proc_do_xprt()
In the original code, the "if (*lenp < 0)" check didn't work because
"*lenp" is unsigned. Fortunately, the memory_read_from_buffer() call
will never fail in this context so it doesn't affect runtime.
Signed-off-by: J. Bruce Fields <[email protected]>
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 5c9f5bca4d99..3aad6ef18504 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -63,19 +63,20 @@ static int proc_do_xprt(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[256];
- size_t len;
+ ssize_t len;
if (write || *ppos) {
*lenp = 0;
return 0;
}
len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
- *lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
+ len = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
- if (*lenp < 0) {
+ if (len < 0) {
*lenp = 0;
return -EINVAL;
}
+ *lenp = len;
return 0;
}
Bruce, thanks for catching my bug.
Acked-by: Dan Carpenter <[email protected]>
Do want me to do anything, because it seems like you already fixed my
patch?
regards,
dan carpenter