On 2015-01-10 01:48, Greg KH wrote: > On Sat, Jan 10, 2015 at 01:08:58AM +0100, Stefan Agner wrote: >> If the serial port gets closed while a RX transfer is in progress, >> the timer might fire after the serial port shutdown finished. This >> leads in a NULL pointer dereference: >> >> [ 7.508324] Unable to handle kernel NULL pointer dereference at virtual address 00000000 >> [ 7.516590] pgd = 86348000 >> [ 7.519445] [00000000] *pgd=86179831, *pte=00000000, *ppte=00000000 >> [ 7.526145] Internal error: Oops: 17 [#1] ARM >> [ 7.530611] Modules linked in: >> [ 7.533876] CPU: 0 PID: 123 Comm: systemd Not tainted 3.19.0-rc3-00004-g5b11ea7 #1778 >> [ 7.541827] Hardware name: Freescale Vybrid VF610 (Device Tree) >> [ 7.547862] task: 861c3400 ti: 86ac8000 task.ti: 86ac8000 >> [ 7.553392] PC is at lpuart_timer_func+0x24/0xf8 >> [ 7.558127] LR is at lpuart_timer_func+0x20/0xf8 >> [ 7.562857] pc : [<802df99c>] lr : [<802df998>] psr: 600b0113 >> [ 7.562857] sp : 86ac9b90 ip : 86ac9b90 fp : 86ac9bbc >> [ 7.574467] r10: 80817180 r9 : 80817b98 r8 : 80817998 >> [ 7.579803] r7 : 807acee0 r6 : 86989000 r5 : 00000100 r4 : 86997210 >> [ 7.586444] r3 : 86ac8000 r2 : 86ac9bc0 r1 : 86997210 r0 : 00000000 >> [ 7.593085] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user >> [ 7.600341] Control: 10c5387d Table: 86348059 DAC: 00000015 >> [ 7.606203] Process systemd (pid: 123, stack limit = 0x86ac8230) >> >> Setup the timer on UART startup which allows to delete the timer >> unconditionally on shutdown. This also saves the initialization >> on each transfer. >> >> Signed-off-by: Stefan Agner <stefan@xxxxxxxx> >> --- >> drivers/tty/serial/fsl_lpuart.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) > > Do stable kernels care about this as well, or is this just a regression > from 3.18? This is an issue since DMA support for lpuart was included in the kernel, which was in 3.14. -- Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
