Re: [PATCH 2/2] Coccinelle: extend memdup_user rule with vmemdup_user()

Re: [PATCH 2/2] Coccinelle: extend memdup_user rule with vmemdup_user()

[Markus Elfring]

> Add vmemdup_user() transformations to the memdup_user.cocci rule.
> Commit 50fd2f298bef ("new primitive: vmemdup_user()") introduced
> vmemdup_user(). The function uses kvmalloc with GPF_USER flag.

Such a software evolution is also interesting.


> +@depends on patch@


> +-  to = \(kvmalloc\|kvzalloc\)(size,\(GFP_KERNEL\|GFP_USER\));
> ++  to = vmemdup_user(from,size);

How do you think about to achieve the desired data processing by the application
of a SmPL disjunction like the following?

 to =
(
-     \( kmalloc \| kzalloc \) (size, \( GFP_KERNEL \| GFP_USER \))
+     memdup_user(from, size)
|
-     \( kvmalloc \| kvzalloc \) (size, \( GFP_KERNEL \| GFP_USER \))
+     vmemdup_user(from, size)
)
 ;


Unfortunately, the Coccinelle software does not like the following
SmPL code variant so far.

 to =
(
-     \( kmalloc \| kzalloc \)
+     memdup_user
|
-     \( kvmalloc \| kvzalloc \)
+     vmemdup_user
)
                 (
-                 size, \( GFP_KERNEL \| GFP_USER \)
+                 from, size
                 );


Message:
25: no available token to attach to


Regards,
Markus

Re: [2/2] Coccinelle: memdup_user: Extending data processing for special tokens

[Markus Elfring]

> Unfortunately, the Coccinelle software does not like the following
> SmPL code variant so far.
>
>  to =
> (
> -     \( kmalloc \| kzalloc \)
> +     memdup_user
> |
> -     \( kvmalloc \| kvzalloc \)
> +     vmemdup_user
> )
>                  (
> -                 size, \( GFP_KERNEL \| GFP_USER \)
> +                 from, size
>                  );
>
>
> Message:
> 25: no available token to attach to

I have adjusted a bit of OCaml source code.
Thus I could see where such information was provided.
https://github.com/coccinelle/coccinelle/blob/7cf2c23e64066d5249a64a316cc5347831f7a63f/parsing_cocci/insert_plus.ml#L1041

…
  | (((infop,count,pcode) as p) :: ps) as all ->
      (* …
	 modifications.  for the moment, we thus give an error, asking the
	 user to rewrite the semantic patch. *)
      if greater_than_end infop infom1 || is_minus m1 || !empty_isos
…


Will the referenced comment get any more software development attention?

Regards,
Markus

Re: [PATCH 2/2] Coccinelle: extend memdup_user rule with vmemdup_user()

[Markus Elfring]

> +@rv depends on !patch@
> +expression from,to,size;
> +position p;
> +statement S1,S2;
> +@@
> +
> +*  to = \(kvmalloc@p\|kvzalloc@p\)(size,\(GFP_KERNEL\|GFP_USER\));
> +   if (to==NULL || ...) S1
> +   if (copy_from_user(to, from, size) != 0)
> +   S2

How does the SmPL asterisk functionality fit to the operation
modes “org” and “report”?


> +@script:python depends on org && r@

I find the modification of SmPL rule dependencies also interesting.
Are these specifications really required?

Regards,
Markus

[PATCH 2/2] Coccinelle: extend memdup_user rule with vmemdup_user()

[Denis Efremov]

Add vmemdup_user() transformations to the memdup_user.cocci rule.
Commit 50fd2f298bef ("new primitive: vmemdup_user()") introduced
vmemdup_user(). The function uses kvmalloc with GPF_USER flag.

Signed-off-by: Denis Efremov <efremov@linux.com>
---
 scripts/coccinelle/api/memdup_user.cocci | 49 +++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/scripts/coccinelle/api/memdup_user.cocci b/scripts/coccinelle/api/memdup_user.cocci
index 49f487e6a5c8..a50def35136e 100644
--- a/scripts/coccinelle/api/memdup_user.cocci
+++ b/scripts/coccinelle/api/memdup_user.cocci
@@ -37,6 +37,28 @@ identifier l1,l2;
 -    ...+>
 -  }
 
+@depends on patch@
+expression from,to,size;
+identifier l1,l2;
+@@
+
+-  to = \(kvmalloc\|kvzalloc\)(size,\(GFP_KERNEL\|GFP_USER\));
++  to = vmemdup_user(from,size);
+   if (
+-      to==NULL
++      IS_ERR(to)
+                 || ...) {
+   <+... when != goto l1;
+-  -ENOMEM
++  PTR_ERR(to)
+   ...+>
+   }
+-  if (copy_from_user(to, from, size) != 0) {
+-    <+... when != goto l2;
+-    -EFAULT
+-    ...+>
+-  }
+
 @r depends on !patch@
 expression from,to,size;
 position p;
@@ -48,14 +70,37 @@ statement S1,S2;
    if (copy_from_user(to, from, size) != 0)
    S2
 
-@script:python depends on org@
+@rv depends on !patch@
+expression from,to,size;
+position p;
+statement S1,S2;
+@@
+
+*  to = \(kvmalloc@p\|kvzalloc@p\)(size,\(GFP_KERNEL\|GFP_USER\));
+   if (to==NULL || ...) S1
+   if (copy_from_user(to, from, size) != 0)
+   S2
+
+@script:python depends on org && r@
 p << r.p;
 @@
 
 coccilib.org.print_todo(p[0], "WARNING opportunity for memdup_user")
 
-@script:python depends on report@
+@script:python depends on report && r@
 p << r.p;
 @@
 
 coccilib.report.print_report(p[0], "WARNING opportunity for memdup_user")
+
+@script:python depends on org && rv@
+p << rv.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING opportunity for vmemdup_user")
+
+@script:python depends on report && rv@
+p << rv.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING opportunity for vmemdup_user")
-- 
2.26.2