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Message-Id: <20190929163028.9665-2-romain.perier@gmail.com>
Date: Sun, 29 Sep 2019 18:30:13 +0200
From: Romain Perier <romain.perier@...il.com>
To: kernel-hardening@...ts.openwall.com
Cc: Kees Cook <keescook@...omium.org>,
Romain Perier <romain.perier@...il.com>
Subject: [PRE-REVIEW PATCH 01/16] tasklet: Prepare to change tasklet callback argument type
Nowadays, modern kernel subsystems that use callbacks pass the data
structure associated with a given callback as argument to the callback.
The tasklet subsystem remains the one to pass callback argument as an
arbitrary unsigned long argument. This has several problems:
- This keeps an extra field for storing the argument in each tasklet
data structure, it bloats the tasklet_struct structure with a redundant
.data field
- No type checking cannot be performed on this argument. Instead of
using container_of() like other callback subsystems, it forces callbacks
to do explicit type cast of the unsigned long argument into the required
object type.
- Buffer overflows can overwrite the .function and the .data field, so
an attacker can easily overwrite the function and its first argument
to whatever it wants.
This adds a new tasklet initialization API which will gradually replace
the existing one.
This work is greatly inspired from the timer_struct conversion series,
see commit e99e88a9d ("treewide: setup_timer() -> timer_setup()")
Signed-off-by: Romain Perier <romain.perier@...il.com>
---
include/linux/interrupt.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 89fc59dab57d..f5332ae2dbeb 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -673,6 +673,18 @@ extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
extern void tasklet_init(struct tasklet_struct *t,
void (*func)(unsigned long), unsigned long data);
+#define TASKLET_DATA_TYPE unsigned long
+#define TASKLET_FUNC_TYPE void (*)(TASKLET_DATA_TYPE)
+
+#define from_tasklet(var, callback_tasklet, tasklet_fieldname) \
+ container_of(callback_tasklet, typeof(*var), tasklet_fieldname)
+
+static inline void tasklet_setup(struct tasklet_struct *t,
+ void (*callback)(struct tasklet_struct *))
+{
+ tasklet_init(t, (TASKLET_FUNC_TYPE)callback, (TASKLET_DATA_TYPE)t);
+}
+
/*
* Autoprobing for irqs:
*
--
2.23.0
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