* [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
@ 2008-11-14 18:05 ` Julia Lawall
0 siblings, 0 replies; 6+ messages in thread
From: Julia Lawall @ 2008-11-14 18:05 UTC (permalink / raw)
To: srostedt, linux-kernel, kernel-janitors
From: Julia Lawall <julia@diku.dk>
Error handling code following a kzalloc should free the allocated data.
The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,l;
position p1,p2;
expression *ptr != NULL;
@@
(
if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) = NULL) S
|
x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x = NULL) S
)
<... when != x
when != if (...) { <+...x...+> }
x->f = E
...>
(
return \(0\|<+...x...+>\|ptr\);
|
return@p2 ...;
)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
---
kernel/trace/trace.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 697eda3..d86e325 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
mutex_unlock(&trace_types_lock);
+ kfree(iter);
return ERR_PTR(-ENOMEM);
}
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
@ 2008-11-14 18:05 ` Julia Lawall
0 siblings, 0 replies; 6+ messages in thread
From: Julia Lawall @ 2008-11-14 18:05 UTC (permalink / raw)
To: srostedt, linux-kernel, kernel-janitors
From: Julia Lawall <julia@diku.dk>
Error handling code following a kzalloc should free the allocated data.
The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,l;
position p1,p2;
expression *ptr != NULL;
@@
(
if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) == NULL) S
|
x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
)
<... when != x
when != if (...) { <+...x...+> }
x->f = E
...>
(
return \(0\|<+...x...+>\|ptr\);
|
return@p2 ...;
)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
---
kernel/trace/trace.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 697eda3..d86e325 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
mutex_unlock(&trace_types_lock);
+ kfree(iter);
return ERR_PTR(-ENOMEM);
}
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
2008-11-14 18:05 ` Julia Lawall
@ 2008-11-18 22:42 ` Andrew Morton
-1 siblings, 0 replies; 6+ messages in thread
From: Andrew Morton @ 2008-11-18 22:42 UTC (permalink / raw)
To: Julia Lawall; +Cc: srostedt, linux-kernel, kernel-janitors, Ingo Molnar
On Fri, 14 Nov 2008 19:05:31 +0100 (CET)
Julia Lawall <julia@diku.dk> wrote:
> From: Julia Lawall <julia@diku.dk>
>
> Error handling code following a kzalloc should free the allocated data.
>
> The semantic match that finds the problem is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
>
> // <smpl>
> @r exists@
> local idexpression x;
> statement S;
> expression E;
> identifier f,l;
> position p1,p2;
> expression *ptr != NULL;
> @@
>
> (
> if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) = NULL) S
> |
> x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
> ...
> if (x = NULL) S
> )
> <... when != x
> when != if (...) { <+...x...+> }
> x->f = E
> ...>
> (
> return \(0\|<+...x...+>\|ptr\);
> |
> return@p2 ...;
> )
>
> @script:python@
> p1 << r.p1;
> p2 << r.p2;
> @@
>
> print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@diku.dk>
> ---
> kernel/trace/trace.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 697eda3..d86e325 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
> ring_buffer_read_finish(iter->buffer_iter[cpu]);
> }
> mutex_unlock(&trace_types_lock);
> + kfree(iter);
>
> return ERR_PTR(-ENOMEM);
> }
Nobody seems to have applied this to anything yet?
That function really needs help. Sometimes it will return NULL and
will set *ret. Other times it will return ERR_PTR(-ENOMEM) and will
fail to write anything to *ret. One caller (tracing_open) ignores the
return value. Another caller (tracing_lt_open) tests the
possibly-uninitialised `ret' and then blindly dereferences the
possibly-IS_ERR return value.
Or something like that. I looked at it long enough to convince myself
that it needs fixing ;)
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
@ 2008-11-18 22:42 ` Andrew Morton
0 siblings, 0 replies; 6+ messages in thread
From: Andrew Morton @ 2008-11-18 22:42 UTC (permalink / raw)
To: Julia Lawall; +Cc: srostedt, linux-kernel, kernel-janitors, Ingo Molnar
On Fri, 14 Nov 2008 19:05:31 +0100 (CET)
Julia Lawall <julia@diku.dk> wrote:
> From: Julia Lawall <julia@diku.dk>
>
> Error handling code following a kzalloc should free the allocated data.
>
> The semantic match that finds the problem is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
>
> // <smpl>
> @r exists@
> local idexpression x;
> statement S;
> expression E;
> identifier f,l;
> position p1,p2;
> expression *ptr != NULL;
> @@
>
> (
> if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) == NULL) S
> |
> x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
> ...
> if (x == NULL) S
> )
> <... when != x
> when != if (...) { <+...x...+> }
> x->f = E
> ...>
> (
> return \(0\|<+...x...+>\|ptr\);
> |
> return@p2 ...;
> )
>
> @script:python@
> p1 << r.p1;
> p2 << r.p2;
> @@
>
> print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@diku.dk>
> ---
> kernel/trace/trace.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 697eda3..d86e325 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
> ring_buffer_read_finish(iter->buffer_iter[cpu]);
> }
> mutex_unlock(&trace_types_lock);
> + kfree(iter);
>
> return ERR_PTR(-ENOMEM);
> }
Nobody seems to have applied this to anything yet?
That function really needs help. Sometimes it will return NULL and
will set *ret. Other times it will return ERR_PTR(-ENOMEM) and will
fail to write anything to *ret. One caller (tracing_open) ignores the
return value. Another caller (tracing_lt_open) tests the
possibly-uninitialised `ret' and then blindly dereferences the
possibly-IS_ERR return value.
Or something like that. I looked at it long enough to convince myself
that it needs fixing ;)
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
2008-11-18 22:42 ` Andrew Morton
@ 2008-11-19 8:52 ` Ingo Molnar
-1 siblings, 0 replies; 6+ messages in thread
From: Ingo Molnar @ 2008-11-19 8:52 UTC (permalink / raw)
To: Andrew Morton; +Cc: Julia Lawall, srostedt, linux-kernel, kernel-janitors
* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Fri, 14 Nov 2008 19:05:31 +0100 (CET)
> Julia Lawall <julia@diku.dk> wrote:
>
> > From: Julia Lawall <julia@diku.dk>
> >
> > Error handling code following a kzalloc should free the allocated data.
> >
> > The semantic match that finds the problem is as follows:
> > (http://www.emn.fr/x-info/coccinelle/)
> >
> > // <smpl>
> > @r exists@
> > local idexpression x;
> > statement S;
> > expression E;
> > identifier f,l;
> > position p1,p2;
> > expression *ptr != NULL;
> > @@
> >
> > (
> > if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) = NULL) S
> > |
> > x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
> > ...
> > if (x = NULL) S
> > )
> > <... when != x
> > when != if (...) { <+...x...+> }
> > x->f = E
> > ...>
> > (
> > return \(0\|<+...x...+>\|ptr\);
> > |
> > return@p2 ...;
> > )
> >
> > @script:python@
> > p1 << r.p1;
> > p2 << r.p2;
> > @@
> >
> > print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <julia@diku.dk>
> > ---
> > kernel/trace/trace.c | 1 +
> > 1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 697eda3..d86e325 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
> > ring_buffer_read_finish(iter->buffer_iter[cpu]);
> > }
> > mutex_unlock(&trace_types_lock);
> > + kfree(iter);
> >
> > return ERR_PTR(-ENOMEM);
> > }
>
> Nobody seems to have applied this to anything yet?
it's in tip/tracing/urgent:
0bb943c: tracing: kernel/trace/trace.c: introduce missing kfree()
> That function really needs help. Sometimes it will return NULL and
> will set *ret. Other times it will return ERR_PTR(-ENOMEM) and will
> fail to write anything to *ret. One caller (tracing_open) ignores
> the return value. Another caller (tracing_lt_open) tests the
> possibly-uninitialised `ret' and then blindly dereferences the
> possibly-IS_ERR return value.
>
> Or something like that. I looked at it long enough to convince
> myself that it needs fixing ;)
agreed, it's messy. At minimum the ordering is wrong: it should not
return the iterator but 'ret' - the _iterator_ value can then be a
side-effect (dependent on the return value being fine).
the usage site clearly shows the problem:
static int tracing_open(struct inode *inode, struct file *file)
{
int ret;
__tracing_open(inode, file, &ret);
return ret;
}
that could then be a simple:
static int tracing_open(struct inode *inode, struct file *file)
{
return __tracing_open(inode, file, NULL);
}
and we wouldnt allocate an iterator if the iter ptr is NULL. (which we
seem to leak in tracing_open() right now!)
Ingo
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree
@ 2008-11-19 8:52 ` Ingo Molnar
0 siblings, 0 replies; 6+ messages in thread
From: Ingo Molnar @ 2008-11-19 8:52 UTC (permalink / raw)
To: Andrew Morton; +Cc: Julia Lawall, srostedt, linux-kernel, kernel-janitors
* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Fri, 14 Nov 2008 19:05:31 +0100 (CET)
> Julia Lawall <julia@diku.dk> wrote:
>
> > From: Julia Lawall <julia@diku.dk>
> >
> > Error handling code following a kzalloc should free the allocated data.
> >
> > The semantic match that finds the problem is as follows:
> > (http://www.emn.fr/x-info/coccinelle/)
> >
> > // <smpl>
> > @r exists@
> > local idexpression x;
> > statement S;
> > expression E;
> > identifier f,l;
> > position p1,p2;
> > expression *ptr != NULL;
> > @@
> >
> > (
> > if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) == NULL) S
> > |
> > x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
> > ...
> > if (x == NULL) S
> > )
> > <... when != x
> > when != if (...) { <+...x...+> }
> > x->f = E
> > ...>
> > (
> > return \(0\|<+...x...+>\|ptr\);
> > |
> > return@p2 ...;
> > )
> >
> > @script:python@
> > p1 << r.p1;
> > p2 << r.p2;
> > @@
> >
> > print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <julia@diku.dk>
> > ---
> > kernel/trace/trace.c | 1 +
> > 1 files changed, 1 insertions(+), 0 deletions(-)
> >
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 697eda3..d86e325 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -1936,6 +1936,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
> > ring_buffer_read_finish(iter->buffer_iter[cpu]);
> > }
> > mutex_unlock(&trace_types_lock);
> > + kfree(iter);
> >
> > return ERR_PTR(-ENOMEM);
> > }
>
> Nobody seems to have applied this to anything yet?
it's in tip/tracing/urgent:
0bb943c: tracing: kernel/trace/trace.c: introduce missing kfree()
> That function really needs help. Sometimes it will return NULL and
> will set *ret. Other times it will return ERR_PTR(-ENOMEM) and will
> fail to write anything to *ret. One caller (tracing_open) ignores
> the return value. Another caller (tracing_lt_open) tests the
> possibly-uninitialised `ret' and then blindly dereferences the
> possibly-IS_ERR return value.
>
> Or something like that. I looked at it long enough to convince
> myself that it needs fixing ;)
agreed, it's messy. At minimum the ordering is wrong: it should not
return the iterator but 'ret' - the _iterator_ value can then be a
side-effect (dependent on the return value being fine).
the usage site clearly shows the problem:
static int tracing_open(struct inode *inode, struct file *file)
{
int ret;
__tracing_open(inode, file, &ret);
return ret;
}
that could then be a simple:
static int tracing_open(struct inode *inode, struct file *file)
{
return __tracing_open(inode, file, NULL);
}
and we wouldnt allocate an iterator if the iter ptr is NULL. (which we
seem to leak in tracing_open() right now!)
Ingo
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2008-11-19 8:53 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2008-11-14 18:05 [PATCH 1/3] kernel/trace/trace.c: introduce missing kfree Julia Lawall
2008-11-14 18:05 ` Julia Lawall
2008-11-18 22:42 ` Andrew Morton
2008-11-18 22:42 ` Andrew Morton
2008-11-19 8:52 ` Ingo Molnar
2008-11-19 8:52 ` Ingo Molnar
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