On Thu, Aug 05, 2021 at 02:49:05PM -0700, Dhananjay Phadke wrote: > Similar NULL deref was originally fixed by graceful teardown sequence - > > https://lore.kernel.org/linux-i2c/1597106560-79693-1-git-send-email-dphadke@xxxxxxxxxxxxxxxxxxx > > After this, a tasklet was added to take care of FIFO full condition for large i2c > transaction. > > https://lore.kernel.org/linux-arm-kernel/20201102035433.6774-1-rayagonda.kokatanur@xxxxxxxxxxxx/ > > This introduced regression, a new race condition between tasklet enabling > interrupts and client unreg teardown sequence. > > Kill tasklet before unreg_slave() masks bits in IE_OFFSET. > Updated teardown sequence - > (1) disable_irq() > (2) Kill tasklet > (3) Mask event enable bits in control reg > (4) Erase slave address (avoid further writes to rx fifo) > (5) Flush tx and rx FIFOs > (6) Clear pending event (interrupt) bits in status reg > (7) Set client pointer to NULL > (8) enable_irq() > > -- > > Unable to handle kernel read from unreadable memory at virtual address 0000000000000320 > Mem abort info: > ESR = 0x96000004 > EC = 0x25: DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > Data abort info: > ISV = 0, ISS = 0x00000004 > CM = 0, WnR = 0 > user pgtable: 4k pages, 48-bit VAs, pgdp=000000009212a000 > [0000000000000320] pgd=0000000000000000, p4d=0000000000000000 > Internal error: Oops: 96000004 [#1] SMP > CPU: 0 PID: 0 Comm: swapper/0 Tainted: G O > Hardware name: Overlake (DT) > pstate: 40400085 (nZcv daIf +PAN -UAO -TCO BTYPE=--) > pc : bcm_iproc_i2c_slave_isr+0x2b8/0x8e4 > lr : bcm_iproc_i2c_slave_isr+0x1c8/0x8e4 > sp : ffff800010003e70 > x29: ffff800010003e80 x28: ffffda017acdc000 > x27: ffffda017b0ae000 x26: ffff800010004000 > x25: ffff800010000000 x24: ffffda017af4a168 > x23: 0000000000000073 x22: 0000000000000000 > x21: 0000000001400000 x20: 0000000001000000 > x19: ffff06f09583f880 x18: 00000000fa83b2da > x17: 000000000000b67e x16: 0000000002edb2f3 > x15: 00000000000002c7 x14: 00000000000002c7 > x13: 0000000000000006 x12: 0000000000000033 > x11: 0000000000000000 x10: 0000000001000000 > x9 : 0000000003289312 x8 : 0000000003289311 > x7 : 02d0cd03a303adbc x6 : 02d18e7f0a4dfc6c > x5 : 02edb2f33f76ea68 x4 : 00000000fa83b2da > x3 : ffffda017af43cd0 x2 : ffff800010003e74 > x1 : 0000000001400000 x0 : 0000000000000000 > Call trace: > bcm_iproc_i2c_slave_isr+0x2b8/0x8e4 > bcm_iproc_i2c_isr+0x178/0x290 > __handle_irq_event_percpu+0xd0/0x200 > handle_irq_event+0x60/0x1a0 > handle_fasteoi_irq+0x130/0x220 > __handle_domain_irq+0x8c/0xcc > gic_handle_irq+0xc0/0x120 > el1_irq+0xcc/0x180 > finish_task_switch+0x100/0x1d8 > __schedule+0x61c/0x7a0 > schedule_idle+0x28/0x44 > do_idle+0x254/0x28c > cpu_startup_entry+0x28/0x2c > rest_init+0xc4/0xd0 > arch_call_rest_init+0x14/0x1c > start_kernel+0x33c/0x3b8 > Code: f9423260 910013e2 11000509 b9047a69 (f9419009) Applied to for-current, thanks!
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