Messages in this thread Patches in this message | | | Date | Fri, 27 Jun 2003 01:17:37 +0900 | From | Hiroshi Inoue <> | Subject | [PATCH] Repeatable kernel crash in tty_io.c (2.5.73 & 2.4.21) |
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Hi,
I found that kernel 2.5.73 (and also 2.4.21) crashed in drivers/char/tty_io.c at situation described below.
1. login to tty2 (not tty1) 2. start kon (Kanji cONsole emulator, console which support Japanese characters) 3. exit kon 4. logout
This crash is repeatable. I use Redhat 9 on ThinkPad T20.
These patches (for kernel 2.5.73 and 2.4.21) prevent list_del() when the list is empty. In kernel 2.5.73, these applying list_del() to empty list seems to be occured very often (not only at the above situation). I think this might be harmful.
Regards, Hiroshi Inoue
--- /usr/src/linux-2.5.73.orig/drivers/char/tty_io.c 2003-06-25 10:45:30.000000000 +0900 +++ /usr/src/linux-2.5.73/drivers/char/tty_io.c 2003-06-27 00:17:12.000000000 +0900 @@ -1018,9 +1018,11 @@ } o_tty->magic = 0; o_tty->driver->refcount--; - file_list_lock(); - list_del(&o_tty->tty_files); - file_list_unlock(); + if (o_tty->tty_files.next != &o_tty->tty_files) { + file_list_lock(); + list_del(&o_tty->tty_files); + file_list_unlock(); + } free_tty_struct(o_tty); } @@ -1032,9 +1034,11 @@ } tty->magic = 0; tty->driver->refcount--; - file_list_lock(); - list_del(&tty->tty_files); - file_list_unlock(); + if (tty->tty_files.next != &tty->tty_files) { + file_list_lock(); + list_del(&tty->tty_files); + file_list_unlock(); + } module_put(tty->driver->owner); free_tty_struct(tty); } @@ -1372,7 +1376,10 @@ } filp->private_data = tty; - file_move(filp, &tty->tty_files); + if (filp->f_list.next == &filp->f_list) + list_add(&filp->f_list, &tty->tty_files); + else + file_move(filp, &tty->tty_files); check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER)
--- /usr/src/linux-2.4.21.orig/drivers/char/tty_io.c 2003-06-13 23:51:33.000000000 +0900 +++ /usr/src/linux-2.4.21/drivers/char/tty_io.c 2003-06-27 00:34:53.798982568 +0900 @@ -1043,7 +1043,8 @@ } o_tty->magic = 0; (*o_tty->driver.refcount)--; - list_del(&o_tty->tty_files); + if (o_tty->tty_files.next != &o_tty->tty_files) + list_del(&o_tty->tty_files); free_tty_struct(o_tty); } @@ -1055,7 +1056,8 @@ } tty->magic = 0; (*tty->driver.refcount)--; - list_del(&tty->tty_files); + if (tty->tty_files.next != &tty->tty_files) + list_del(&tty->tty_files); free_tty_struct(tty); } @@ -1383,7 +1385,10 @@ init_dev_done: #endif filp->private_data = tty; - file_move(filp, &tty->tty_files); + if (filp->f_list.next == &filp->f_list) + list_add(&filp->f_list, &tty->tty_files); + else + file_move(filp, &tty->tty_files); check_tty_count(tty, "tty_open"); if (tty->driver.type == TTY_DRIVER_TYPE_PTY && tty->driver.subtype == PTY_TYPE_MASTER)
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