Messages in this thread | | | Subject | Re: [PATCH] staging: ion: fix corruption of ion_import_dma_buf | From | Laura Abbott <> | Date | Thu, 10 Sep 2015 09:44:28 -0700 |
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On 09/09/2015 10:41 PM, Colin Cross wrote: > On Wed, Sep 9, 2015 at 10:19 AM, Laura Abbott <labbott@redhat.com> wrote: >> (adding Colin and John) >> >> >> On 09/09/2015 12:41 AM, Shawn Lin wrote: >>> >>> 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> >>> --- >>> >>> 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 eec878e..32e7b5c 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) { >>> >> >> So the patch looks correct but the locking change there seems like it was >> added >> deliberately. Colin/John, do you remember why the locking for >> ion_import_dma_buf >> changed? Was there a deadlock condition somewhere? >> >> Thanks, >> Laura > > I can't see any reason to not hold the mutex across ion_handle_create. > The patch that introduced the bug > (83271f6262c91a49df325c52bec8f00f4de294ca, ion: hold reference to > handle after ion_uhandle_get) required that the mutex not be held > around the call to ion_handle_put, but didn't affect > ion_handle_create.
Thanks for confirming. With that,
Reviewed-by: Laura Abbott <labbott@redhat.com>
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