4.14-stable review patch. If anyone has any objections, please let me know.
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From: Sean Young sean@mess.org
[not upstream as the driver is deleted in 4.16 - gregkh]
Whenever poll is called, the reference count is increased but never decreased. This means that on rmmod, the lirc_thread is not stopped, and will trample over freed memory.
Zilog/Hauppauge IR driver unloaded BUG: unable to handle kernel paging request at ffffffffc17ba640 Oops: 0010 [#1] SMP CPU: 1 PID: 667 Comm: zilog-rx-i2c-1 Tainted: P C OE 4.13.16-302.fc27.x86_64 #1 Hardware name: Gigabyte Technology Co., Ltd. GA-MA790FXT-UD5P/GA-MA790FXT-UD5P, BIOS F6 08/06/2009 task: ffff964eb452ca00 task.stack: ffffb254414dc000 RIP: 0010:0xffffffffc17ba640 RSP: 0018:ffffb254414dfe78 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff964ec1b35890 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000246 RDI: 0000000000000246 RBP: ffffb254414dff00 R08: 000000000000036e R09: ffff964ecfc8dfd0 R10: ffffb254414dfe78 R11: 00000000000f4240 R12: ffff964ec2bf28a0 R13: ffff964ec1b358a8 R14: ffff964ec1b358d0 R15: ffff964ec1b35800 FS: 0000000000000000(0000) GS:ffff964ecfc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc17ba640 CR3: 000000023058c000 CR4: 00000000000006e0 Call Trace: kthread+0x125/0x140 ? kthread_park+0x60/0x60 ? do_syscall_64+0x67/0x140 ret_from_fork+0x25/0x30 Code: Bad RIP value. RIP: 0xffffffffc17ba640 RSP: ffffb254414dfe78 CR2: ffffffffc17ba640
Note that zilog-rx-i2c-1 should have exited by now, but hasn't due to the missing put in poll().
This code has been replaced completely in kernel v4.16 by a new driver, see commit acaa34bf06e9 ("media: rc: implement zilog transmitter"), and commit f95367a7b758 ("media: staging: remove lirc_zilog driver").
Cc: stable@vger.kernel.org # v4.15- (all up to and including v4.15) Reported-by: Warren Sturm warren.sturm@gmail.com Tested-by: Warren Sturm warren.sturm@gmail.com Signed-off-by: Sean Young sean@mess.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/staging/media/lirc/lirc_zilog.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/staging/media/lirc/lirc_zilog.c +++ b/drivers/staging/media/lirc/lirc_zilog.c @@ -1228,6 +1228,7 @@ static unsigned int poll(struct file *fi
dev_dbg(ir->l.dev, "%s result = %s\n", __func__, ret ? "POLLIN|POLLRDNORM" : "none"); + put_ir_rx(rx, false); return ret; }