patch "staging: ion: fix corruption of ion_import_dma_buf" added to staging-linus

patch "staging: ion: fix corruption of ion_import_dma_buf" added to staging-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: ion: fix corruption of ion_import_dma_buf

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 6fa92e2bcf6390e64895b12761e851c452d87bd8 Mon Sep 17 00:00:00 2001
From: Shawn Lin <shawn.lin@rock-chips.com>
Date: Wed, 9 Sep 2015 15:41:52 +0800
Subject: staging: ion: fix corruption of ion_import_dma_buf

we found this issue but still exit in lastest kernel. Simply
keep ion_handle_create under mutex_lock to avoid this race.

WARNING: CPU: 2 PID: 2648 at drivers/staging/android/ion/ion.c:512 ion_handle_add+0xb4/0xc0()
ion_handle_add: buffer already found.
Modules linked in: iwlmvm iwlwifi mac80211 cfg80211 compat
CPU: 2 PID: 2648 Comm: TimedEventQueue Tainted: G        W    3.14.0 #7
 00000000 00000000 9a3efd2c 80faf273 9a3efd6c 9a3efd5c 80935dc9 811d7fd3
 9a3efd88 00000a58 812208a0 00000200 80e128d4 80e128d4 8d4ae00c a8cd8600
 a8cd8094 9a3efd74 80935e0e 00000009 9a3efd6c 811d7fd3 9a3efd88 9a3efd9c
Call Trace:
  [<80faf273>] dump_stack+0x48/0x69
  [<80935dc9>] warn_slowpath_common+0x79/0x90
  [<80e128d4>] ? ion_handle_add+0xb4/0xc0
  [<80e128d4>] ? ion_handle_add+0xb4/0xc0
  [<80935e0e>] warn_slowpath_fmt+0x2e/0x30
  [<80e128d4>] ion_handle_add+0xb4/0xc0
  [<80e144cc>] ion_import_dma_buf+0x8c/0x110
  [<80c517c4>] reg_init+0x364/0x7d0
  [<80993363>] ? futex_wait+0x123/0x210
  [<80992e0e>] ? get_futex_key+0x16e/0x1e0
  [<8099308f>] ? futex_wake+0x5f/0x120
  [<80c51e19>] vpu_service_ioctl+0x1e9/0x500
  [<80994aec>] ? do_futex+0xec/0x8e0
  [<80971080>] ? prepare_to_wait_event+0xc0/0xc0
  [<80c51c30>] ? reg_init+0x7d0/0x7d0
  [<80a22562>] do_vfs_ioctl+0x2d2/0x4c0
  [<80b198ad>] ? inode_has_perm.isra.41+0x2d/0x40
  [<80b199cf>] ? file_has_perm+0x7f/0x90
  [<80b1a5f7>] ? selinux_file_ioctl+0x47/0xf0
  [<80a227a8>] SyS_ioctl+0x58/0x80
  [<80fb45e8>] syscall_call+0x7/0x7
  [<80fb0000>] ? mmc_do_calc_max_discard+0xab/0xe4

Fixes: 83271f626 ("ion: hold reference to handle...")
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Laura Abbott <labbott@redhat.com>
Cc: stable <stable@vger.kernel.org> # 3.14+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/android/ion/ion.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 217aa537c4eb..6e8d8392ca38 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -1179,13 +1179,13 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
 		mutex_unlock(&client->lock);
 		goto end;
 	}
-	mutex_unlock(&client->lock);
 
 	handle = ion_handle_create(client, buffer);
-	if (IS_ERR(handle))
+	if (IS_ERR(handle)) {
+		mutex_unlock(&client->lock);
 		goto end;
+	}
 
-	mutex_lock(&client->lock);
 	ret = ion_handle_add(client, handle);
 	mutex_unlock(&client->lock);
 	if (ret) {
-- 
2.5.2