Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/directory v6

From: Andrew Morton
Date: Thu Sep 08 2011 - 19:52:45 EST


On Thu, 8 Sep 2011 10:04:05 +0400
Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:

> fs, proc: Introduce the /proc/<pid>/map_files/ directory v11

Ho hum, I've pretty much run out of excuses to avoid merging this.

except...

We don't really want to bloat fs/proc/base.o by 4k until all the other
things which support c/r are mergeable and we know that the whole
project is actually useful. When will we be at this stage?

<looks at the warning>

fs/proc/base.c: In function 'proc_map_files_instantiate':
fs/proc/base.c:2348: warning: assignment from incompatible pointer type

err, that code will crash at runtime and it isn't trivial to fix.
How could this happen?

>
> ...
>
> + if (fa)
> + flex_array_free(fa);
>
> ...
>
> + if (fa)
> + flex_array_free(fa);

I think I'll do this:

From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

Lots of callers are avoiding passing NULL into flex_array_free(). Move
the check into flex_array_free() in the usual fashion.

Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

fs/proc/base.c | 6 ++----
lib/flex_array.c | 2 ++
security/selinux/ss/policydb.c | 9 +++------
3 files changed, 7 insertions(+), 10 deletions(-)

diff -puN lib/flex_array.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free lib/flex_array.c
--- a/lib/flex_array.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free
+++ a/lib/flex_array.c
@@ -142,6 +142,8 @@ EXPORT_SYMBOL(flex_array_free_parts);

void flex_array_free(struct flex_array *fa)
{
+ if (!fa)
+ return;
flex_array_free_parts(fa);
kfree(fa);
}
diff -puN fs/proc/base.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free fs/proc/base.c
--- a/fs/proc/base.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free
+++ a/fs/proc/base.c
@@ -2514,8 +2514,7 @@ static int proc_map_files_readdir(struct
fa = flex_array_alloc(sizeof(info), nr_files, GFP_KERNEL);
if (!fa || flex_array_prealloc(fa, 0, nr_files, GFP_KERNEL)) {
ret = -ENOMEM;
- if (fa)
- flex_array_free(fa);
+ flex_array_free(fa);
up_read(&mm->mmap_sem);
mmput(mm);
goto out;
@@ -2556,8 +2555,7 @@ static int proc_map_files_readdir(struct
p = flex_array_get(fa, i);
fput(p->file);
}
- if (fa)
- flex_array_free(fa);
+ flex_array_free(fa);
mmput(mm);
}
}
diff -puN security/selinux/ss/policydb.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free security/selinux/ss/policydb.c
--- a/security/selinux/ss/policydb.c~lib-flex_arrayc-accept-null-arg-to-flex_array_free
+++ a/security/selinux/ss/policydb.c
@@ -769,16 +769,13 @@ void policydb_destroy(struct policydb *p
hashtab_destroy(p->symtab[i].table);
}

- for (i = 0; i < SYM_NUM; i++) {
- if (p->sym_val_to_name[i])
- flex_array_free(p->sym_val_to_name[i]);
- }
+ for (i = 0; i < SYM_NUM; i++)
+ flex_array_free(p->sym_val_to_name[i]);

kfree(p->class_val_to_struct);
kfree(p->role_val_to_struct);
kfree(p->user_val_to_struct);
- if (p->type_val_to_struct_array)
- flex_array_free(p->type_val_to_struct_array);
+ flex_array_free(p->type_val_to_struct_array);

avtab_destroy(&p->te_avtab);

_

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