user/sven/linux.git/drivers/tty, branch v5.16.16

serial: stm32: prevent TDR register overwrite when sending x_char

2022-03-08T18:14:04Z

[ Upstream commit d3d079bde07e1b7deaeb57506dc0b86010121d17 ] When sending x_char in stm32_usart_transmit_chars(), driver can overwrite the value of TDR register by the value of x_char. If this happens, the previous value that was present in TDR register will not be sent through uart. This code checks if the previous value in TDR register is sent before writing the x_char value into register. Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Cc: stable Signed-off-by: Valentin Caron Link: https://lore.kernel.org/r/20220111164441.6178-2-valentin.caron@foss.st.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

tty: n_gsm: fix deadlock in gsmtty_open()

2022-03-02T10:51:21Z

commit a2ab75b8e76e455af7867e3835fd9cdf386b508f upstream. In the current implementation the user may open a virtual tty which then could fail to establish the underlying DLCI. The function gsmtty_open() gets stuck in tty_port_block_til_ready() while waiting for a carrier rise. This happens if the remote side fails to acknowledge the link establishment request in time or completely. At some point gsm_dlci_close() is called to abort the link establishment attempt. The function tries to inform the associated virtual tty by performing a hangup. But the blocking loop within tty_port_block_til_ready() is not informed about this event. The patch proposed here fixes this by resetting the initialization state of the virtual tty to ensure the loop exits and triggering it to make tty_port_block_til_ready() return. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-7-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix wrong modem processing in convergence layer type 2

2022-03-02T10:51:21Z

commit 687f9ad43c52501f46164758e908a5dd181a87fc upstream. The function gsm_process_modem() exists to handle modem status bits of incoming frames. This includes incoming MSC (modem status command) frames and convergence layer type 2 data frames. The function, however, was only designed to handle MSC frames as it expects the command length. Within gsm_dlci_data() it is wrongly assumed that this is the same as the data frame length. This is only true if the data frame contains only 1 byte of payload. This patch names the length parameter of gsm_process_modem() in a generic manner to reflect its association. It also corrects all calls to the function to handle the variable number of modem status octets correctly in both cases. Fixes: 7263287af93d ("tty: n_gsm: Fixed logic to decode break signal from modem status") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-6-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix wrong tty control line for flow control

2022-03-02T10:51:21Z

commit c19d93542a6081577e6da9bf5e887979c72e80c1 upstream. tty flow control is handled via gsmtty_throttle() and gsmtty_unthrottle(). Both functions propagate the outgoing hardware flow control state to the remote side via MSC (modem status command) frames. The local state is taken from the RTS (ready to send) flag of the tty. However, RTS gets mapped to DTR (data terminal ready), which is wrong. This patch corrects this by mapping RTS to RTS. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-5-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix NULL pointer access due to DLCI release

2022-03-02T10:51:20Z

commit 96b169f05cdcc844b400695184d77e42071d14f2 upstream. The here fixed commit made the tty hangup asynchronous to avoid a circular locking warning. I could not reproduce this warning. Furthermore, due to the asynchronous hangup the function call now gets queued up while the underlying tty is being freed. Depending on the timing this results in a NULL pointer access in the global work queue scheduler. To be precise in process_one_work(). Therefore, the previous commit made the issue worse which it tried to fix. This patch fixes this by falling back to the old behavior which uses a blocking tty hangup call before freeing up the associated tty. Fixes: 7030082a7415 ("tty: n_gsm: avoid recursive locking with async port hangup") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-4-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix proper link termination after failed open

2022-03-02T10:51:20Z

commit e3b7468f082d106459e86e8dc6fb9bdd65553433 upstream. Trying to open a DLCI by sending a SABM frame may fail with a timeout. The link is closed on the initiator side without informing the responder about this event. The responder assumes the link is open after sending a UA frame to answer the SABM frame. The link gets stuck in a half open state. This patch fixes this by initiating the proper link termination procedure after link setup timeout instead of silently closing it down. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-3-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix encoding of command/response bit

2022-03-02T10:51:20Z

commit 57435c42400ec147a527b2313188b649e81e449e upstream. n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010. See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516 The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. Chapter 5.2.1.2 describes the encoding of the C/R (command/response) bit. Table 1 shows that the actual encoding of the C/R bit is inverted if the associated frame is sent by the responder. The referenced commit fixed here further broke the internal meaning of this bit in the outgoing path by always setting the C/R bit regardless of the frame type. This patch fixes both by setting the C/R bit always consistently for command (1) and response (0) frames and inverting it later for the responder where necessary. The meaning of this bit in the debug output is being preserved and shows the bit as if it was encoded by the initiator. This reflects only the frame type rather than the encoded combination of communication side and frame type. Fixes: cc0f42122a7e ("tty: n_gsm: Modify CR,PF bit when config requester") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-2-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: fix encoding of control signal octet bit DV

2022-03-02T10:51:20Z

commit 737b0ef3be6b319d6c1fd64193d1603311969326 upstream. n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010. See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516 The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. Chapter 5.4.6.3.7 describes the encoding of the control signal octet used by the MSC (modem status command). The same encoding is also used in convergence layer type 2 as described in chapter 5.5.2. Table 7 and 24 both require the DV (data valid) bit to be set 1 for outgoing control signal octets sent by the DTE (data terminal equipment), i.e. for the initiator side. Currently, the DV bit is only set if CD (carrier detect) is on, regardless of the side. This patch fixes this behavior by setting the DV bit on the initiator side unconditionally. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-1-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman

sc16is7xx: Fix for incorrect data being transmitted

2022-03-02T10:51:13Z

commit eebb0f4e894f1e9577a56b337693d1051dd6ebfd upstream. UART drivers are meant to use the port spinlock within certain methods, to protect against reentrancy. The sc16is7xx driver does very little locking, presumably because when added it triggers "scheduling while atomic" errors. This is due to the use of mutexes within the regmap abstraction layer, and the mutex implementation's habit of sleeping the current thread while waiting for access. Unfortunately this lack of interlocking can lead to corruption of outbound data, which occurs when the buffer used for I2C transmission is used simultaneously by two threads - a work queue thread running sc16is7xx_tx_proc, and an IRQ thread in sc16is7xx_port_irq, both of which can call sc16is7xx_handle_tx. An earlier patch added efr_lock, a mutex that controls access to the EFR register. This mutex is already claimed in the IRQ handler, and all that is required is to claim the same mutex in sc16is7xx_tx_proc. See: https://github.com/raspberrypi/linux/issues/4885 Fixes: 6393ff1c4435 ("sc16is7xx: Use threaded IRQ") Cc: stable Signed-off-by: Phil Elwell Link: https://lore.kernel.org/r/20220216160802.1026013-1-phil@raspberrypi.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

tty: n_tty: do not look ahead for EOL character past the end of the buffer

2022-02-23T11:06:02Z

commit 3593030761630e09200072a4bd06468892c27be3 upstream. Daniel Gibson reports that the n_tty code gets line termination wrong in very specific cases: "If you feed a line with exactly 64 chars + terminating newline, and directly afterwards (without reading) another line into a pseudo terminal, the the first read() on the other side will return the 64 char line *without* terminating newline, and the next read() will return the missing terminating newline AND the complete next line (if it fits in the buffer)" and bisected the behavior to commit 3b830a9c34d5 ("tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer"). Now, digging deeper, it turns out that the behavior isn't exactly new: what changed in commit 3b830a9c34d5 was that the tty line discipline .read() function is now passed an intermediate kernel buffer rather than the final user space buffer. And that intermediate kernel buffer is 64 bytes in size - thus that special case with exactly 64 bytes plus terminating newline. The same problem did exist before, but historically the boundary was not the 64-byte chunk, but the user-supplied buffer size, which is obviously generally bigger (and potentially bigger than N_TTY_BUF_SIZE, which would hide the issue entirely). The reason is that the n_tty canon_copy_from_read_buf() code would look ahead for the EOL character one byte further than it would actually copy. It would then decide that it had found the terminator, and unmark it as an EOL character - which in turn explains why the next read wouldn't then be terminated by it. Now, the reason it did all this in the first place is related to some historical and pretty obscure EOF behavior, see commit ac8f3bf8832a ("n_tty: Fix poll() after buffer-limited eof push read") and commit 40d5e0905a03 ("n_tty: Fix EOF push handling"). And the reason for the EOL confusion is that we treat EOF as a special EOL condition, with the EOL character being NUL (aka "__DISABLED_CHAR" in the kernel sources). So that EOF look-ahead also affects the normal EOL handling. This patch just removes the look-ahead that causes problems, because EOL is much more critical than the historical "EOF in the middle of a line that coincides with the end of the buffer" handling ever was. Now, it is possible that we should indeed re-introduce the "look at next character to see if it's a EOF" behavior, but if so, that should be done not at the kernel buffer chunk boundary in canon_copy_from_read_buf(), but at a higher level, when we run out of the user buffer. In particular, the place to do that would be at the top of 'n_tty_read()', where we check if it's a continuation of a previously started read, and there is no more buffer space left, we could decide to just eat the __DISABLED_CHAR at that point. But that would be a separate patch, because I suspect nobody actually cares, and I'd like to get a report about it before bothering. Fixes: 3b830a9c34d5 ("tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer") Fixes: ac8f3bf8832a ("n_tty: Fix poll() after buffer-limited eof push read") Fixes: 40d5e0905a03 ("n_tty: Fix EOF push handling") Link: https://bugzilla.kernel.org/show_bug.cgi?id=215611 Reported-and-tested-by: Daniel Gibson Cc: Peter Hurley Cc: Greg Kroah-Hartman Cc: Jiri Slaby Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman