Messages in this thread | | | Date | Tue, 21 Feb 2017 18:59:12 -0800 | From | Sodagudi Prasad <> | Subject | Re: Free after use in fw_pm_notify()->kill_requests_without_uevent() due pending_fw_head |
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On 2017-01-03 07:19, Greg KH wrote: > On Tue, Jan 03, 2017 at 06:44:03AM -0800, Sodagudi Prasad wrote: >> >> Hi All, >> >> Device has crashed due to memory access after free while >> pending_fw_head >> list accessed. Kernel 4.4 stable version is used to reproduce this use >> after >> free. >> ------------------------------------------------------------------------------------------ >> [ 9031.178428] Unable to handle kernel paging request at virtual >> address >> 6b6b6b6b6b6b6b6b >> [ 9031.178508] pgd = ffffffc0de9d2000 >> [ 9031.185888] [6b6b6b6b6b6b6b6b] *pgd=0000000000000000, >> *pud=0000000000000000 >> [ 9031.253045] ------------[ cut here ]------------ >> [ 9031.253100] Kernel BUG at ffffff800864c0a0 [verbose debug info >> unavailable] >> [ 9031.256860] Internal error: Oops - BUG: 96000004 [#1] PREEMPT SMP >> [ 9031.263539] Modules linked in: >> [ 9031.272708] CPU: 6 PID: 1373 Comm: system_server Tainted: G >> W L >> 4.4.16+ #1 >> [ 9031.280648] task: ffffffc0d1a1d700 ti: ffffffc0d1a2c000 task.ti: >> ffffffc0d1a2c000 >> [ 9031.287776] PC is at fw_pm_notify+0x84/0x19c >> [ 9031.295215] LR is at fw_pm_notify+0x60/0x19c >> [ 9031.511559] [] fw_pm_notify+0x84/0x19c >> [ 9031.519355] [] notifier_call_chain+0x58/0x8c >> [ 9031.524739] [] __blocking_notifier_call_chain+0x54/0x70 >> [ 9031.530387] [] blocking_notifier_call_chain+0x38/0x44 >> [ 9031.537243] [] pm_notifier_call_chain+0x28/0x48 >> [ 9031.543662] [] pm_suspend+0x278/0x674 >> [ 9031.549906] [] state_store+0x58/0x90 >> [ 9031.554942] [] kobj_attr_store+0x18/0x28 >> [ 9031.560154] [] sysfs_kf_write+0x5c/0x68 >> [ 9031.565620] [] kernfs_fop_write+0x114/0x16c >> [ 9031.571092] [] __vfs_write+0x48/0xf0 >> [ 9031.576816] [] vfs_write+0xb8/0x150 >> [ 9031.581848] [] SyS_write+0x58/0x94 >> [ 9031.586973] [] el0_svc_naked+0x24/0x28 >> ----------------------------------------------------------------------------------------------- >> >> Kernel panic is observed during device suspend/resume path in the >> kill_requests_without_uevent() called from fw_pm_notify(). >> when pending_list of a firmware_buf is accessed 0x6b(free pattern) >> pattern >> observed. Based on this firmware_buf is freed even if firmware_buf is >> part >> of >> pending_fw_head list. > > What are you doing in userspace to trigger this problem? What kernel > driver is this happening with? Device continuous suspend and resume is happening here. I think, echo mem > /sys/power/state issued here. It is not clear what driver involved here, because after firmware_buf is freed all memory gets filled with 0x6b pattern.
> > And 4.4.16 is pretty old, can you try 4.9? We don't have system which runs on new kernels. Looking for possible reasons/path, how firmware_buf can get freed when that in pending_fw_head list.
> > thanks, > > greg k-h
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