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

[Julia Lawall]

On Sat, 30 May 2020, Denis Efremov wrote:

> 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 
> ---
>  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
> +-...+>
> +-  }
> +

This could protect against modifying vmemdup_user.  Probably the original
rule should protect against modifying memdup_user as well.

julia




>  @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
>
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Re: [Cocci] [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
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Re: [Cocci] [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
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[Cocci] [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 
---
 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

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