Re: [PATCH v3 1/3] coccinelle: api: extend memdup_user transformation with GFP_USER

Re: [PATCH v3 1/3] coccinelle: api: extend memdup_user transformation with GFP_USER

[Markus Elfring]

> Match GFP_USER and optional __GFP_NOWARN allocations with
> memdup_user.cocci rule.

I suggest to clarify software design consequences according to such information
a bit more.


I find it helpful if you would have included also my email address directly
in the message field “To” or “Cc”.
Are there further reasons to consider for the extension of the recipient lists?


> +-  to = \(kmalloc\|kzalloc\)
> +-		(size,\(GFP_KERNEL\|GFP_USER\|
> +-		      \(GFP_KERNEL\|GFP_USER\)|__GFP_NOWARN\));

* Would you ever dare to specify such a source code search pattern
  on a single line?

* I find the specification of SmPL disjunctions questionable
  for the determination of relevant flags.
  Could previous patch review trigger concerns and further considerations
  for the proper handling of optional source code parts?


> +*  to = \(kmalloc@p\|kzalloc@p\)
> +		(size,\(GFP_KERNEL\|GFP_USER\|
> +		      \(GFP_KERNEL\|GFP_USER\)|__GFP_NOWARN\));

Would you like to use the SmPL asterisk really only for a single line?


How will the chances evolve to continue the clarification also for
the open issue “Safer source code analysis by "memdup_user.cocci"”?
https://github.com/coccinelle/coccinelle/issues/78

Regards,
Markus

[PATCH v3 1/3] coccinelle: api: extend memdup_user transformation with GFP_USER

[Denis Efremov]

Match GFP_USER and optional __GFP_NOWARN allocations with
memdup_user.cocci rule.
Commit 6c2c97a24f09 ("memdup_user(): switch to GFP_USER") switched
memdup_user() from GFP_KERNEL to GFP_USER. In almost all cases it
is still a good idea to recommend memdup_user() for GFP_KERNEL
allocations. The motivation behind altering memdup_user() to GFP_USER:
https://lkml.org/lkml/2018/1/6/333

Signed-off-by: Denis Efremov <efremov@linux.com>
---
 scripts/coccinelle/api/memdup_user.cocci | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/scripts/coccinelle/api/memdup_user.cocci b/scripts/coccinelle/api/memdup_user.cocci
index c809ab10bbce..0e29d41ecab8 100644
--- a/scripts/coccinelle/api/memdup_user.cocci
+++ b/scripts/coccinelle/api/memdup_user.cocci
@@ -20,7 +20,9 @@ expression from,to,size;
 identifier l1,l2;
 @@
 
--  to = \(kmalloc\|kzalloc\)(size,GFP_KERNEL);
+-  to = \(kmalloc\|kzalloc\)
+-		(size,\(GFP_KERNEL\|GFP_USER\|
+-		      \(GFP_KERNEL\|GFP_USER\)|__GFP_NOWARN\));
 +  to = memdup_user(from,size);
    if (
 -      to==NULL
@@ -43,7 +45,9 @@ position p;
 statement S1,S2;
 @@
 
-*  to = \(kmalloc@p\|kzalloc@p\)(size,GFP_KERNEL);
+*  to = \(kmalloc@p\|kzalloc@p\)
+		(size,\(GFP_KERNEL\|GFP_USER\|
+		      \(GFP_KERNEL\|GFP_USER\)|__GFP_NOWARN\));
    if (to==NULL || ...) S1
    if (copy_from_user(to, from, size) != 0)
    S2
-- 
2.26.2