p could be NULL and passing into PTR_ERR
Signed-off-by: Vasyl Gomonovych <[email protected]>
---
fs/seq_file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 4be761c..8b700b9 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -262,8 +262,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
size_t offs = m->count;
loff_t next = pos;
p = m->op->next(m, p, &next);
- if (!p || IS_ERR(p)) {
- err = PTR_ERR(p);
+ if (IS_ERR(p)) {
+ err = (!p ? -EFAULT : PTR_ERR(p));
break;
}
err = m->op->show(m, p);
--
1.9.1
On Fri, Dec 08, 2017 at 12:03:07AM +0100, Vasyl Gomonovych wrote:
> p could be NULL and passing into PTR_ERR
What makes you think this is correct?
To quote the documentation:
The next function to implement is called, amazingly, next(); its job is to
move the iterator forward to the next position in the sequence. The
example module can simply increment the position by one; more useful
modules will do what is needed to step through some data structure. The
next() function returns a new iterator, or NULL if the sequence is
complete. Here's the example version:
So if it returns NULL, we want to set err to 0 and break. Which is, um,
exactly what the code does.
Did you test this at all?
> Signed-off-by: Vasyl Gomonovych <[email protected]>
> ---
> fs/seq_file.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/seq_file.c b/fs/seq_file.c
> index 4be761c..8b700b9 100644
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -262,8 +262,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
> size_t offs = m->count;
> loff_t next = pos;
> p = m->op->next(m, p, &next);
> - if (!p || IS_ERR(p)) {
> - err = PTR_ERR(p);
> + if (IS_ERR(p)) {
> + err = (!p ? -EFAULT : PTR_ERR(p));
> break;
> }
> err = m->op->show(m, p);
> --
> 1.9.1
>
On Fri, Dec 08, 2017 at 12:03:07AM +0100, Vasyl Gomonovych wrote:
> p could be NULL and passing into PTR_ERR
>
> Signed-off-by: Vasyl Gomonovych <[email protected]>
> ---
> fs/seq_file.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/seq_file.c b/fs/seq_file.c
> index 4be761c..8b700b9 100644
> --- a/fs/seq_file.c
> +++ b/fs/seq_file.c
> @@ -262,8 +262,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
> size_t offs = m->count;
> loff_t next = pos;
> p = m->op->next(m, p, &next);
> - if (!p || IS_ERR(p)) {
> - err = PTR_ERR(p);
> + if (IS_ERR(p)) {
> + err = (!p ? -EFAULT : PTR_ERR(p));
What does it fix, if I might ask? And while we are at it, would
you mind explaining the reasoning behind that change? Or, say,
testing done to it...
On Thu, Dec 07, 2017 at 11:23:26PM +0000, Al Viro wrote:
> On Fri, Dec 08, 2017 at 12:03:07AM +0100, Vasyl Gomonovych wrote:
> > p could be NULL and passing into PTR_ERR
> >
> > Signed-off-by: Vasyl Gomonovych <[email protected]>
> > ---
> > fs/seq_file.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/seq_file.c b/fs/seq_file.c
> > index 4be761c..8b700b9 100644
> > --- a/fs/seq_file.c
> > +++ b/fs/seq_file.c
> > @@ -262,8 +262,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
> > size_t offs = m->count;
> > loff_t next = pos;
> > p = m->op->next(m, p, &next);
> > - if (!p || IS_ERR(p)) {
> > - err = PTR_ERR(p);
> > + if (IS_ERR(p)) {
> > + err = (!p ? -EFAULT : PTR_ERR(p));
>
> What does it fix, if I might ask? And while we are at it, would
> you mind explaining the reasoning behind that change? Or, say,
> testing done to it...
While we are at it, where has that -EFAULT come from? And how
would it be ever reached, seeing that IS_ERR(NULL) is false?
Hi,
Guys sorry for this idiotic piece of code.
Yesterday after doc seq_file.txt read I did not catch real way of work there.
And made this shit.
Sorry.
Regards Vasyl
On Fri, Dec 8, 2017 at 12:26 AM, Al Viro <[email protected]> wrote:
> On Thu, Dec 07, 2017 at 11:23:26PM +0000, Al Viro wrote:
>> On Fri, Dec 08, 2017 at 12:03:07AM +0100, Vasyl Gomonovych wrote:
>> > p could be NULL and passing into PTR_ERR
>> >
>> > Signed-off-by: Vasyl Gomonovych <[email protected]>
>> > ---
>> > fs/seq_file.c | 4 ++--
>> > 1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/fs/seq_file.c b/fs/seq_file.c
>> > index 4be761c..8b700b9 100644
>> > --- a/fs/seq_file.c
>> > +++ b/fs/seq_file.c
>> > @@ -262,8 +262,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
>> > size_t offs = m->count;
>> > loff_t next = pos;
>> > p = m->op->next(m, p, &next);
>> > - if (!p || IS_ERR(p)) {
>> > - err = PTR_ERR(p);
>> > + if (IS_ERR(p)) {
>> > + err = (!p ? -EFAULT : PTR_ERR(p));
>>
>> What does it fix, if I might ask? And while we are at it, would
>> you mind explaining the reasoning behind that change? Or, say,
>> testing done to it...
>
> While we are at it, where has that -EFAULT come from? And how
> would it be ever reached, seeing that IS_ERR(NULL) is false?
--
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