This reverts commit c284ee2cf12b55fa8496b2d098bf0938688f1c1c. Turns out the locking was incorrect. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Cc: Chao Bi <chao.bi@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With multiple, concurrent readers (each waiting to acquire the atomic_read_lock mutex), a departing reader may mistakenly reset minimum_to_wake after a new reader has already set a new value. Protect the minimum_to_wake reset with the atomic_read_lock critical section. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A common security idiom is to hangup the current tty (via vhangup()) after forking but before execing a root shell. This hangs up any existing opens which other processes may have and ensures subsequent opens have the necessary permissions to open the root shell tty/pty. Reset the TTY_HUPPED state after the driver has successfully returned the opened tty (perform the reset while the tty is locked to avoid racing with concurrent hangups). Reported-by: Heorhi Valakhanovich <valahanovich@tut.by> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> # 3.12 Tested-by: Heorhi Valakhanovich <valahanovich@tut.by> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When booting a multi-platform m68k kernel on a non-Amiga with "console=ttyS0" on the kernel command line, it crashes with: Unable to handle kernel access at virtual address 81dff01c Oops: 00000000 PC: [<001e09a8>] serial_console_write+0xc/0x70 Add the missing platform check to amiserial_console_init() to fix this. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When booting a multi-platform m68k kernel on a non-Mac with "console=ttyS0" on the kernel command line, it crashes with: Unable to handle kernel NULL pointer dereference at virtual address (null) Oops: 00000000 PC: [<0013ad28>] __pmz_startup+0x32/0x2a0 ... Call Trace: [<002c5d3e>] pmz_console_setup+0x64/0xe4 The normal tty driver doesn't crash, because init_pmz() checks pmz_ports_count again after calling pmz_probe(). In the serial console initialization path, pmz_console_init() doesn't do this, causing the driver to crash later. Add a check for pmz_ports_count to fix this. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Finn Thain <fthain@telegraphics.com.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ttyA has ld associated to n_gsm, when ttyA is closing, it triggers
to release gsmttyB's ld data dlci[B], then race would happen if gsmttyB
is opening in parallel.
Here are race cases we found recently in test:
CASE #1
====================================================================
releasing dlci[B] race with gsmtty_install(gsmttyB), then panic
in gsmtty_open(gsmttyB), as below:
tty_release(ttyA) tty_open(gsmttyB)
| |
----- gsmtty_install(gsmttyB)
| |
----- gsm_dlci_alloc(gsmttyB) => alloc dlci[B]
tty_ldisc_release(ttyA) -----
| |
gsm_dlci_release(dlci[B]) -----
| |
gsm_dlci_free(dlci[B]) -----
| |
----- gsmtty_open(gsmttyB)
gsmtty_open()
{
struct gsm_dlci *dlci = tty->driver_data; => here it uses dlci[B]
...
}
In gsmtty_open(gsmttyA), it uses dlci[B] which was release, so hit a panic.
=====================================================================
CASE #2
=====================================================================
releasing dlci[0] race with gsmtty_install(gsmttyB), then panic
in gsmtty_open(), as below:
tty_release(ttyA) tty_open(gsmttyB)
| |
----- gsmtty_install(gsmttyB)
| |
----- gsm_dlci_alloc(gsmttyB) => alloc dlci[B]
| |
----- gsmtty_open(gsmttyB) fail
| |
----- tty_release(gsmttyB)
| |
----- gsmtty_close(gsmttyB)
| |
----- gsmtty_detach_dlci(dlci[B])
| |
----- dlci_put(dlci[B])
| |
tty_ldisc_release(ttyA) -----
| |
gsm_dlci_release(dlci[0]) -----
| |
gsm_dlci_free(dlci[0]) -----
| |
----- dlci_put(dlci[0])
In gsmtty_detach_dlci(dlci[B]), it tries to use dlci[0] which was released,
then hit panic.
=====================================================================
IMHO, n_gsm tty operations would refer released ldisc, as long as
gsm_dlci_release() has chance to release ldisc data when some gsmtty operations
are not completed..
This patch is try to avoid it by:
1) in n_gsm driver, use a global gsm spin lock to avoid gsm_dlci_release() run in
parallel with gsmtty_install();
2) Increase dlci's ref count in gsmtty_install() instead of in gsmtty_open(), the
purpose is to prevent gsm_dlci_release() releasing dlci after gsmtty_install()
allocats dlci but before gsmtty_open increases dlci's ref count;
3) Decrease dlci's ref count in gsmtty_remove(), which is a tty framework api, and
this is the opposite process of step 2).
Signed-off-by: Chao Bi <chao.bi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 9326b047e4fd4a8da72e59d913214a1803e9709c includes a typo of "8350_core" instead of "8250_core", so correct it. Fixes kernel bugzilla #60724: https://bugzilla.kernel.org/show_bug.cgi?id=60724 Reported-by: Christoph Biedl <bugzilla.kernel.bpeb@manchmal.in-ulm.de> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Although the maximum allowable canonical line is specified to be 255 bytes (MAX_CANON), the practical limit has actually been the size of the line discipline read buffer (N_TTY_BUF_SIZE == 4096). Commit 32f13521ca68bc624ff6effc77f308a52b038bf0, n_tty: Line copy to user buffer in canonical mode, limited the line copy to 4095 bytes. With a completely full line discipline read buffer and a userspace buffer > 4095, _no_ data was copied, and the read() syscall returned 0, indicating EOF. Fix the interval arithmetic to compute the correct number of bytes to copy to userspace in the range [1..4096]. Cc: <stable@vger.kernel.org> # 3.12.x Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit cbfd0340ae1993378fd47179db949e050e16e697, 'n_tty: Process echoes in blocks', introduced an error when consuming the echo buffer tail to prevent buffer overrun, where the incorrect operation code byte is checked to determine how far to advance the tail to the next echo byte. Check the correct byte for the echo operation code byte. Cc: <stable@vger.kernel.org> # 3.12.x : c476f65 tty: incorrect test of echo_buf() result for ECHO_OP_START Cc: <stable@vger.kernel.org> # 3.12.x Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A departing reader must restart a flush_to_ldisc() worker _before_ the next reader enters the read loop; this is to avoid the new reader concluding no more i/o is available and prematurely exiting, when the old reader simply hasn't re-started the worker yet. Cc: stable <stable@vger.kernel.org> # 3.12 Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>