| Message ID | 20201027141758.GA3488087@mwanda (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | net/sunrpc: clean up error checking in proc_do_xprt() | expand |
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 <dan.carpenter@oracle.com> > --- > 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 <dan.carpenter@oracle.com> > > --- > > 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 <dan.carpenter@oracle.com> 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 <dan.carpenter@oracle.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> 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 <dan.carpenter@oracle.com> 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 <bfields@redhat.com> 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 <dan.carpenter@oracle.com>
Do want me to do anything, because it seems like you already fixed my
patch?
regards,
dan carpenter
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; }
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 <dan.carpenter@oracle.com> --- net/sunrpc/sysctl.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)