--- /dev/null
+From 41662f5cc55335807d39404371cfcbb1909304c4 Mon Sep 17 00:00:00 2001
+From: Kees Cook <keescook@chromium.org>
+Date: Wed, 20 Jan 2016 15:00:45 -0800
+Subject: sysctl: enable strict writes
+
+From: Kees Cook <keescook@chromium.org>
+
+commit 41662f5cc55335807d39404371cfcbb1909304c4 upstream.
+
+SYSCTL_WRITES_WARN was added in commit f4aacea2f5d1 ("sysctl: allow for
+strict write position handling"), and released in v3.16 in August of
+2014. Since then I can find only 1 instance of non-zero offset
+writing[1], and it was fixed immediately in CRIU[2]. As such, it
+appears safe to flip this to the strict state now.
+
+[1] https://www.google.com/search?q="when%20file%20position%20was%20not%200"
+[2] http://lists.openvz.org/pipermail/criu/2015-April/019819.html
+
+Signed-off-by: Kees Cook <keescook@chromium.org>
+Cc: "Eric W. Biederman" <ebiederm@xmission.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Sumit Semwal <sumit.semwal@linaro.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ Documentation/sysctl/kernel.txt | 15 +++++++--------
+ kernel/sysctl.c | 2 +-
+ 2 files changed, 8 insertions(+), 9 deletions(-)
+
+--- a/Documentation/sysctl/kernel.txt
++++ b/Documentation/sysctl/kernel.txt
+@@ -775,14 +775,13 @@ via the /proc/sys interface:
+ Each write syscall must fully contain the sysctl value to be
+ written, and multiple writes on the same sysctl file descriptor
+ will rewrite the sysctl value, regardless of file position.
+- 0 - (default) Same behavior as above, but warn about processes that
+- perform writes to a sysctl file descriptor when the file position
+- is not 0.
+- 1 - Respect file position when writing sysctl strings. Multiple writes
+- will append to the sysctl value buffer. Anything past the max length
+- of the sysctl value buffer will be ignored. Writes to numeric sysctl
+- entries must always be at file position 0 and the value must be
+- fully contained in the buffer sent in the write syscall.
++ 0 - Same behavior as above, but warn about processes that perform writes
++ to a sysctl file descriptor when the file position is not 0.
++ 1 - (default) Respect file position when writing sysctl strings. Multiple
++ writes will append to the sysctl value buffer. Anything past the max
++ length of the sysctl value buffer will be ignored. Writes to numeric
++ sysctl entries must always be at file position 0 and the value must
++ be fully contained in the buffer sent in the write syscall.
+
+ ==============================================================
+
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -173,7 +173,7 @@ extern int no_unaligned_warning;
+ #define SYSCTL_WRITES_WARN 0
+ #define SYSCTL_WRITES_STRICT 1
+
+-static int sysctl_writes_strict = SYSCTL_WRITES_WARN;
++static int sysctl_writes_strict = SYSCTL_WRITES_STRICT;
+
+ static int proc_do_cad_pid(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
--- /dev/null
+From b3ce3ce02d146841af012d08506b4071db8ffde3 Mon Sep 17 00:00:00 2001
+From: Baolin Wang <baolin.wang@linaro.org>
+Date: Thu, 8 Dec 2016 19:55:22 +0800
+Subject: usb: gadget: f_fs: Fix possibe deadlock
+
+From: Baolin Wang <baolin.wang@linaro.org>
+
+commit b3ce3ce02d146841af012d08506b4071db8ffde3 upstream.
+
+When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same
+time another core try to attach new UDC, which will cause deadlock as
+below scenario. Thus we should release ffs lock before issuing
+unregister_gadget_item().
+
+[ 52.642225] c1 ======================================================
+[ 52.642228] c1 [ INFO: possible circular locking dependency detected ]
+[ 52.642236] c1 4.4.6+ #1 Tainted: G W O
+[ 52.642241] c1 -------------------------------------------------------
+[ 52.642245] c1 usb ffs open/2808 is trying to acquire lock:
+[ 52.642270] c0 (udc_lock){+.+.+.}, at: [<ffffffc00065aeec>]
+ usb_gadget_unregister_driver+0x3c/0xc8
+[ 52.642272] c1 but task is already holding lock:
+[ 52.642283] c0 (ffs_lock){+.+.+.}, at: [<ffffffc00066b244>]
+ ffs_data_clear+0x30/0x140
+[ 52.642285] c1 which lock already depends on the new lock.
+[ 52.642287] c1
+ the existing dependency chain (in reverse order) is:
+[ 52.642295] c0
+ -> #1 (ffs_lock){+.+.+.}:
+[ 52.642307] c0 [<ffffffc00012340c>] __lock_acquire+0x20f0/0x2238
+[ 52.642314] c0 [<ffffffc000123b54>] lock_acquire+0xe4/0x298
+[ 52.642322] c0 [<ffffffc000aaf6e8>] mutex_lock_nested+0x7c/0x3cc
+[ 52.642328] c0 [<ffffffc00066f7bc>] ffs_func_bind+0x504/0x6e8
+[ 52.642334] c0 [<ffffffc000654004>] usb_add_function+0x84/0x184
+[ 52.642340] c0 [<ffffffc000658ca4>] configfs_composite_bind+0x264/0x39c
+[ 52.642346] c0 [<ffffffc00065b348>] udc_bind_to_driver+0x58/0x11c
+[ 52.642352] c0 [<ffffffc00065b49c>] usb_udc_attach_driver+0x90/0xc8
+[ 52.642358] c0 [<ffffffc0006598e0>] gadget_dev_desc_UDC_store+0xd4/0x128
+[ 52.642369] c0 [<ffffffc0002c14e8>] configfs_write_file+0xd0/0x13c
+[ 52.642376] c0 [<ffffffc00023c054>] vfs_write+0xb8/0x214
+[ 52.642381] c0 [<ffffffc00023cad4>] SyS_write+0x54/0xb0
+[ 52.642388] c0 [<ffffffc000085ff0>] el0_svc_naked+0x24/0x28
+[ 52.642395] c0
+ -> #0 (udc_lock){+.+.+.}:
+[ 52.642401] c0 [<ffffffc00011e3d0>] print_circular_bug+0x84/0x2e4
+[ 52.642407] c0 [<ffffffc000123454>] __lock_acquire+0x2138/0x2238
+[ 52.642412] c0 [<ffffffc000123b54>] lock_acquire+0xe4/0x298
+[ 52.642420] c0 [<ffffffc000aaf6e8>] mutex_lock_nested+0x7c/0x3cc
+[ 52.642427] c0 [<ffffffc00065aeec>] usb_gadget_unregister_driver+0x3c/0xc8
+[ 52.642432] c0 [<ffffffc00065995c>] unregister_gadget_item+0x28/0x44
+[ 52.642439] c0 [<ffffffc00066b34c>] ffs_data_clear+0x138/0x140
+[ 52.642444] c0 [<ffffffc00066b374>] ffs_data_reset+0x20/0x6c
+[ 52.642450] c0 [<ffffffc00066efd0>] ffs_data_closed+0xac/0x12c
+[ 52.642454] c0 [<ffffffc00066f070>] ffs_ep0_release+0x20/0x2c
+[ 52.642460] c0 [<ffffffc00023dbe4>] __fput+0xb0/0x1f4
+[ 52.642466] c0 [<ffffffc00023dd9c>] ____fput+0x20/0x2c
+[ 52.642473] c0 [<ffffffc0000ee944>] task_work_run+0xb4/0xe8
+[ 52.642482] c0 [<ffffffc0000cd45c>] do_exit+0x360/0xb9c
+[ 52.642487] c0 [<ffffffc0000cf228>] do_group_exit+0x4c/0xb0
+[ 52.642494] c0 [<ffffffc0000dd3c8>] get_signal+0x380/0x89c
+[ 52.642501] c0 [<ffffffc00008a8f0>] do_signal+0x154/0x518
+[ 52.642507] c0 [<ffffffc00008af00>] do_notify_resume+0x70/0x78
+[ 52.642512] c0 [<ffffffc000085ee8>] work_pending+0x1c/0x20
+[ 52.642514] c1
+ other info that might help us debug this:
+[ 52.642517] c1 Possible unsafe locking scenario:
+[ 52.642518] c1 CPU0 CPU1
+[ 52.642520] c1 ---- ----
+[ 52.642525] c0 lock(ffs_lock);
+[ 52.642529] c0 lock(udc_lock);
+[ 52.642533] c0 lock(ffs_lock);
+[ 52.642537] c0 lock(udc_lock);
+[ 52.642539] c1
+ *** DEADLOCK ***
+[ 52.642543] c1 1 lock held by usb ffs open/2808:
+[ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: [<ffffffc00066b244>]
+ ffs_data_clear+0x30/0x140
+[ 52.642557] c1 stack backtrace:
+[ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G
+[ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT)
+[ 52.642568] c1 Call trace:
+[ 52.642573] c1 [<ffffffc00008b430>] dump_backtrace+0x0/0x170
+[ 52.642577] c1 [<ffffffc00008b5c0>] show_stack+0x20/0x28
+[ 52.642583] c1 [<ffffffc000422694>] dump_stack+0xa8/0xe0
+[ 52.642587] c1 [<ffffffc00011e548>] print_circular_bug+0x1fc/0x2e4
+[ 52.642591] c1 [<ffffffc000123454>] __lock_acquire+0x2138/0x2238
+[ 52.642595] c1 [<ffffffc000123b54>] lock_acquire+0xe4/0x298
+[ 52.642599] c1 [<ffffffc000aaf6e8>] mutex_lock_nested+0x7c/0x3cc
+[ 52.642604] c1 [<ffffffc00065aeec>] usb_gadget_unregister_driver+0x3c/0xc8
+[ 52.642608] c1 [<ffffffc00065995c>] unregister_gadget_item+0x28/0x44
+[ 52.642613] c1 [<ffffffc00066b34c>] ffs_data_clear+0x138/0x140
+[ 52.642618] c1 [<ffffffc00066b374>] ffs_data_reset+0x20/0x6c
+[ 52.642621] c1 [<ffffffc00066efd0>] ffs_data_closed+0xac/0x12c
+[ 52.642625] c1 [<ffffffc00066f070>] ffs_ep0_release+0x20/0x2c
+[ 52.642629] c1 [<ffffffc00023dbe4>] __fput+0xb0/0x1f4
+[ 52.642633] c1 [<ffffffc00023dd9c>] ____fput+0x20/0x2c
+[ 52.642636] c1 [<ffffffc0000ee944>] task_work_run+0xb4/0xe8
+[ 52.642640] c1 [<ffffffc0000cd45c>] do_exit+0x360/0xb9c
+[ 52.642644] c1 [<ffffffc0000cf228>] do_group_exit+0x4c/0xb0
+[ 52.642647] c1 [<ffffffc0000dd3c8>] get_signal+0x380/0x89c
+[ 52.642651] c1 [<ffffffc00008a8f0>] do_signal+0x154/0x518
+[ 52.642656] c1 [<ffffffc00008af00>] do_notify_resume+0x70/0x78
+[ 52.642659] c1 [<ffffffc000085ee8>] work_pending+0x1c/0x20
+
+Acked-by: Michal Nazarewicz <mina86@mina86.com>
+Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
+Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
+Cc: Jerry Zhang <zhangjerry@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/usb/gadget/function/f_fs.c | 8 ++++++--
+ 1 file changed, 6 insertions(+), 2 deletions(-)
+
+--- a/drivers/usb/gadget/function/f_fs.c
++++ b/drivers/usb/gadget/function/f_fs.c
+@@ -3412,6 +3412,7 @@ static void ffs_closed(struct ffs_data *
+ {
+ struct ffs_dev *ffs_obj;
+ struct f_fs_opts *opts;
++ struct config_item *ci;
+
+ ENTER();
+ ffs_dev_lock();
+@@ -3434,8 +3435,11 @@ static void ffs_closed(struct ffs_data *
+ || !atomic_read(&opts->func_inst.group.cg_item.ci_kref.refcount))
+ goto done;
+
+- unregister_gadget_item(ffs_obj->opts->
+- func_inst.group.cg_item.ci_parent->ci_parent);
++ ci = opts->func_inst.group.cg_item.ci_parent->ci_parent;
++ ffs_dev_unlock();
++
++ unregister_gadget_item(ci);
++ return;
+ done:
+ ffs_dev_unlock();
+ }
projects / thirdparty / kernel / stable-queue.git / commitdiff
