From: "Steven Rostedt (Red Hat)" <[email protected]>
Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
private macro to let callers have a method to know how much of the
seq_buf was written to.
Signed-off-by: Steven Rostedt <[email protected]>
---
include/linux/seq_buf.h | 6 ++++++
kernel/trace/seq_buf.c | 5 +----
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 3e550d214187..8fda502ee630 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
return s->size - s->len;
}
+/* How much buffer was written? */
+static inline unsigned int seq_buf_used(struct seq_buf *s)
+{
+ return min((s)->len, (s)->size);
+}
+
/**
* seq_buf_get_buf - get buffer to write arbitrary data to
* @s: the seq_buf handle
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 4f35a783b82f..3657af4b5f53 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -16,9 +16,6 @@
#include <linux/seq_file.h>
#include <linux/seq_buf.h>
-/* How much buffer is written? */
-#define SEQ_BUF_USED(s) min((s)->len, (s)->size)
-
/**
* seq_buf_print_seq - move the contents of seq_buf into a seq_file
* @m: the seq_file descriptor that is the destination
@@ -28,7 +25,7 @@
*/
int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
{
- unsigned int len = SEQ_BUF_USED(s);
+ unsigned int len = seq_buf_used(s);
return seq_write(m, s->buffer, len);
}
--
2.1.1
On Thu 2014-11-13 20:13:03, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <[email protected]>
>
> Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
> private macro to let callers have a method to know how much of the
> seq_buf was written to.
>
> Signed-off-by: Steven Rostedt <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
The patch is correct. But we should move it before "[RFC][PATCH 17/23
v4] tracing: Have seq_buf use full buffer" and use it everywhere
any code is accessing the internal buffer using the seq.len value.
I mean to solve the potential buffer overflows mentioned for
"[RFC][PATCH 13/23 v4] tracing: Create seq_buf layer in trace_seq"
Best Regards,
Petr
> ---
> include/linux/seq_buf.h | 6 ++++++
> kernel/trace/seq_buf.c | 5 +----
> 2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> index 3e550d214187..8fda502ee630 100644
> --- a/include/linux/seq_buf.h
> +++ b/include/linux/seq_buf.h
> @@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
> return s->size - s->len;
> }
>
> +/* How much buffer was written? */
> +static inline unsigned int seq_buf_used(struct seq_buf *s)
> +{
> + return min((s)->len, (s)->size);
> +}
> +
> /**
> * seq_buf_get_buf - get buffer to write arbitrary data to
> * @s: the seq_buf handle
> diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
> index 4f35a783b82f..3657af4b5f53 100644
> --- a/kernel/trace/seq_buf.c
> +++ b/kernel/trace/seq_buf.c
> @@ -16,9 +16,6 @@
> #include <linux/seq_file.h>
> #include <linux/seq_buf.h>
>
> -/* How much buffer is written? */
> -#define SEQ_BUF_USED(s) min((s)->len, (s)->size)
> -
> /**
> * seq_buf_print_seq - move the contents of seq_buf into a seq_file
> * @m: the seq_file descriptor that is the destination
> @@ -28,7 +25,7 @@
> */
> int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
> {
> - unsigned int len = SEQ_BUF_USED(s);
> + unsigned int len = seq_buf_used(s);
>
> return seq_write(m, s->buffer, len);
> }
> --
> 2.1.1
>
>
On Fri, 14 Nov 2014 18:23:06 +0100
Petr Mladek <[email protected]> wrote:
> On Thu 2014-11-13 20:13:03, Steven Rostedt wrote:
> > From: "Steven Rostedt (Red Hat)" <[email protected]>
> >
> > Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
> > private macro to let callers have a method to know how much of the
> > seq_buf was written to.
> >
> > Signed-off-by: Steven Rostedt <[email protected]>
>
> Reviewed-by: Petr Mladek <[email protected]>
>
> The patch is correct. But we should move it before "[RFC][PATCH 17/23
> v4] tracing: Have seq_buf use full buffer" and use it everywhere
> any code is accessing the internal buffer using the seq.len value.
> I mean to solve the potential buffer overflows mentioned for
> "[RFC][PATCH 13/23 v4] tracing: Create seq_buf layer in trace_seq"
>
> Best Regards,
Bah, I'm getting seq_buf_buffer_left() confused with seq_buf_used().
Yes, this should be moved before hand. I thought it was by looking at:
git show <patch-17-SHA1>:include/linux/seq_buf.h
I saw the seq_buf_buffer_left() and confused that with seq_buf_used()
and said to myself "oh good, it has the function I need". Not!
Thanks,
-- Steve