Re: Patch for panic in n_tty_read()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Alan,

I am not sure if you got my last email, so I'm resending it now:

> I am very sorry, but I don't see it. We didn't held the lock while calling tty_audit_push() before, and we don't hold it after the patch neither. > So what's the locking scheme change here? Is there some binding between n_tty_read() and tty_audit_push() I just don't see?

Please can you advice me why I should check this patch with audit folks?

Thanks a lot,
-Stanislav

>> Looks good to me. However it changes the locking rules on
>> tty_audit_push() so please check the audit folks are ok with it. I don't
>> think that causes any problems.
>>
>> Alan
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ee1c268..54d1fc5 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1832,13 +1832,13 @@ do_it_again:
 
 		if (tty->icanon && !L_EXTPROC(tty)) {
 			/* N.B. avoid overrun if nr == 0 */
+			spin_lock_irqsave(&tty->read_lock, flags);
 			while (nr && tty->read_cnt) {
 				int eol;
 
 				eol = test_and_clear_bit(tty->read_tail,
 						tty->read_flags);
 				c = tty->read_buf[tty->read_tail];
-				spin_lock_irqsave(&tty->read_lock, flags);
 				tty->read_tail = ((tty->read_tail+1) &
 						  (N_TTY_BUF_SIZE-1));
 				tty->read_cnt--;
@@ -1864,6 +1864,7 @@ do_it_again:
 					tty_audit_push(tty);
 					break;
 				}
+				spin_lock_irqsave(&tty->read_lock, flags);
 			}
 			if (retval)
 				break;


[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux PPP]     [Linux FS]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Linmodem]     [Device Mapper]     [Linux Kernel for ARM]

  Powered by Linux