Patchwork [lucid,lucid/fsl-imx51,CVE,2/2] block: Fix io_context leak after failure of clone with CLONE_IO

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Submitter Andy Whitcroft
Date March 1, 2012, 2:45 p.m.
Message ID <1330613143-10318-3-git-send-email-apw@canonical.com>
Download mbox | patch
Permalink /patch/144058/
State New
Headers show

Comments

Andy Whitcroft - March 1, 2012, 2:45 p.m.
From: Louis Rilling <louis.rilling@kerlabs.com>

With CLONE_IO, parent's io_context->nr_tasks is incremented, but never
decremented whenever copy_process() fails afterwards, which prevents
exit_io_context() from calling IO schedulers exit functions.

Give a task_struct to exit_io_context(), and call exit_io_context() instead of
put_io_context() in copy_process() cleanup path.

Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

(cherry picked from commit b69f2292063d2caf37ca9aec7d63ded203701bf3)
CVE-2012-0879
BugLink: http://bugs.launchpad.net/bugs/940743
Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
 block/blk-ioc.c           |   10 +++++-----
 include/linux/iocontext.h |    5 +++--
 kernel/exit.c             |    2 +-
 kernel/fork.c             |    3 ++-
 4 files changed, 11 insertions(+), 9 deletions(-)

Patch

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index dcd0412..cbdabb0 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -66,14 +66,14 @@  static void cfq_exit(struct io_context *ioc)
 }
 
 /* Called by the exitting task */
-void exit_io_context(void)
+void exit_io_context(struct task_struct *task)
 {
 	struct io_context *ioc;
 
-	task_lock(current);
-	ioc = current->io_context;
-	current->io_context = NULL;
-	task_unlock(current);
+	task_lock(task);
+	ioc = task->io_context;
+	task->io_context = NULL;
+	task_unlock(task);
 
 	if (atomic_dec_and_test(&ioc->nr_tasks)) {
 		if (ioc->aic && ioc->aic->exit)
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index eb73632..19abfc1 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -94,14 +94,15 @@  static inline struct io_context *ioc_task_link(struct io_context *ioc)
 	return NULL;
 }
 
+struct task_struct;
 #ifdef CONFIG_BLOCK
 int put_io_context(struct io_context *ioc);
-void exit_io_context(void);
+void exit_io_context(struct task_struct *task);
 struct io_context *get_io_context(gfp_t gfp_flags, int node);
 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 #else
-static inline void exit_io_context(void)
+static inline void exit_io_context(struct task_struct *task)
 {
 }
 
diff --git a/kernel/exit.c b/kernel/exit.c
index 0f8fae3..a2a1659 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1020,7 +1020,7 @@  NORET_TYPE void do_exit(long code)
 	tsk->flags |= PF_EXITPIDONE;
 
 	if (tsk->io_context)
-		exit_io_context();
+		exit_io_context(tsk);
 
 	if (tsk->splice_pipe)
 		__free_pipe_info(tsk->splice_pipe);
diff --git a/kernel/fork.c b/kernel/fork.c
index 4bde56f..cd075bc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1299,7 +1299,8 @@  bad_fork_free_pid:
 	if (pid != &init_struct_pid)
 		free_pid(pid);
 bad_fork_cleanup_io:
-	put_io_context(p->io_context);
+	if (p->io_context)
+		exit_io_context(p);
 bad_fork_cleanup_namespaces:
 	exit_task_namespaces(p);
 bad_fork_cleanup_mm: