kernel.git/drivers/tty/serial/serial_core.c, branch linux-5.4.y

serial: core: check uartclk for zero to avoid divide by zero

2024-08-19T03:33:52Z

commit 6eabce6608d6f3440f4c03aa3d3ef50a47a3d193 upstream. Calling ioctl TIOCSSERIAL with an invalid baud_base can result in uartclk being zero, which will result in a divide by zero error in uart_get_divisor(). The check for uartclk being zero in uart_set_info() needs to be done before other settings are made as subsequent calls to ioctl TIOCSSERIAL for the same port would be impacted if the uartclk check was done where uartclk gets set. Oops: divide error: 0000 PREEMPT SMP KASAN PTI RIP: 0010:uart_get_divisor (drivers/tty/serial/serial_core.c:580) Call Trace: serial8250_get_divisor (drivers/tty/serial/8250/8250_port.c:2576 drivers/tty/serial/8250/8250_port.c:2589) serial8250_do_set_termios (drivers/tty/serial/8250/8250_port.c:502 drivers/tty/serial/8250/8250_port.c:2741) serial8250_set_termios (drivers/tty/serial/8250/8250_port.c:2862) uart_change_line_settings (./include/linux/spinlock.h:376 ./include/linux/serial_core.h:608 drivers/tty/serial/serial_core.c:222) uart_port_startup (drivers/tty/serial/serial_core.c:342) uart_startup (drivers/tty/serial/serial_core.c:368) uart_set_info (drivers/tty/serial/serial_core.c:1034) uart_set_info_user (drivers/tty/serial/serial_core.c:1059) tty_set_serial (drivers/tty/tty_io.c:2637) tty_ioctl (drivers/tty/tty_io.c:2647 drivers/tty/tty_io.c:2791) __x64_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:907 fs/ioctl.c:893 fs/ioctl.c:893) do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1) arch/x86/entry/common.c:83 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Reported-by: syzkaller Cc: stable@vger.kernel.org Signed-off-by: George Kennedy Rule: add Link: https://lore.kernel.org/stable/1721148848-9784-1-git-send-email-george.kennedy%40oracle.com Link: https://lore.kernel.org/r/1721219078-3209-1-git-send-email-george.kennedy@oracle.com Signed-off-by: Greg Kroah-Hartman

serial: Fix incorrect rs485 polarity on uart open

2022-01-27T08:19:49Z

commit d3b3404df318504ec084213ab1065b73f49b0f1d upstream. Commit a6845e1e1b78 ("serial: core: Consider rs485 settings to drive RTS") sought to deassert RTS when opening an rs485-enabled uart port. That way, the transceiver does not occupy the bus until it transmits data. Unfortunately, the commit mixed up the logic and *asserted* RTS instead of *deasserting* it: The commit amended uart_port_dtr_rts(), which raises DTR and RTS when opening an rs232 port. "Raising" actually means lowering the signal that's coming out of the uart, because an rs232 transceiver not only changes a signal's voltage level, it also *inverts* the signal. See the simplified schematic in the MAX232 datasheet for an example: https://www.ti.com/lit/ds/symlink/max232.pdf So, to raise RTS on an rs232 port, TIOCM_RTS is *set* in port->mctrl and that results in the signal being driven low. In contrast to rs232, the signal level for rs485 Transmit Enable is the identity, not the inversion: If the transceiver expects a "high" RTS signal for Transmit Enable, the signal coming out of the uart must also be high, so TIOCM_RTS must be *cleared* in port->mctrl. The commit did the exact opposite, but it's easy to see why given the confusing semantics of rs232 and rs485. Fix it. Fixes: a6845e1e1b78 ("serial: core: Consider rs485 settings to drive RTS") Cc: stable@vger.kernel.org # v4.14+ Cc: Rafael Gago Castano Cc: Jan Kiszka Cc: Su Bao Cheng Signed-off-by: Lukas Wunner Link: https://lore.kernel.org/r/9395767847833f2f3193c49cde38501eeb3b5669.1639821059.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

serial: core: Keep mctrl register state and cached copy in sync

2022-01-27T08:19:46Z

[ Upstream commit 93a770b7e16772530196674ffc79bb13fa927dc6 ] struct uart_port contains a cached copy of the Modem Control signals. It is used to skip register writes in uart_update_mctrl() if the new signal state equals the old signal state. It also avoids a register read to obtain the current state of output signals. When a uart_port is registered, uart_configure_port() changes signal state but neglects to keep the cached copy in sync. That may cause a subsequent register write to be incorrectly skipped. Fix it before it trips somebody up. This behavior has been present ever since the serial core was introduced in 2002: https://git.kernel.org/history/history/c/33c0d1b0c3eb So far it was never an issue because the cached copy is initialized to 0 by kzalloc() and when uart_configure_port() is executed, at most DTR has been set by uart_set_options() or sunsu_console_setup(). Therefore, a stable designation seems unnecessary. Signed-off-by: Lukas Wunner Link: https://lore.kernel.org/r/bceeaba030b028ed810272d55d5fc6f3656ddddb.1641129752.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: core: fix transmit-buffer reset and memleak

2021-12-08T08:01:14Z

commit 00de977f9e0aa9760d9a79d1e41ff780f74e3424 upstream. Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") converted serial core to use tty_port_close() but failed to notice that the transmit buffer still needs to be freed on final close. Not freeing the transmit buffer means that the buffer is no longer cleared on next open so that any ioctl() waiting for the buffer to drain might wait indefinitely (e.g. on termios changes) or that stale data can end up being transmitted in case tx is restarted. Furthermore, the buffer of any port that has been opened would leak on driver unbind. Note that the port lock is held when clearing the buffer pointer due to the ldisc race worked around by commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()"). Also note that the tty-port shutdown() callback is not called for console ports so it is not strictly necessary to free the buffer page after releasing the lock (cf. d72402145ace ("tty/serial: do not free trasnmit buffer page under port lock")). Link: https://lore.kernel.org/r/319321886d97c456203d5c6a576a5480d07c3478.1635781688.git.baruch@tkos.co.il Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") Cc: stable@vger.kernel.org # 4.9 Cc: Rob Herring Reported-by: Baruch Siach Tested-by: Baruch Siach Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20211108085431.12637-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

serial: core: Fix initializing and restoring termios speed

2021-11-17T08:48:25Z

commit 027b57170bf8bb6999a28e4a5f3d78bf1db0f90c upstream. Since commit edc6afc54968 ("tty: switch to ktermios and new framework") termios speed is no longer stored only in c_cflag member but also in new additional c_ispeed and c_ospeed members. If BOTHER flag is set in c_cflag then termios speed is stored only in these new members. Therefore to correctly restore termios speed it is required to store also ispeed and ospeed members, not only cflag member. In case only cflag member with BOTHER flag is restored then functions tty_termios_baud_rate() and tty_termios_input_baud_rate() returns baudrate stored in c_ospeed / c_ispeed member, which is zero as it was not restored too. If reported baudrate is invalid (e.g. zero) then serial core functions report fallback baudrate value 9600. So it means that in this case original baudrate is lost and kernel changes it to value 9600. Simple reproducer of this issue is to boot kernel with following command line argument: "console=ttyXXX,86400" (where ttyXXX is the device name). For speed 86400 there is no Bnnn constant and therefore kernel has to represent this speed via BOTHER c_cflag. Which means that speed is stored only in c_ospeed and c_ispeed members, not in c_cflag anymore. If bootloader correctly configures serial device to speed 86400 then kernel prints boot log to early console at speed speed 86400 without any issue. But after kernel starts initializing real console device ttyXXX then speed is changed to fallback value 9600 because information about speed was lost. This patch fixes above issue by storing and restoring also ispeed and ospeed members, which are required for BOTHER flag. Fixes: edc6afc54968 ("[PATCH] tty: switch to ktermios and new framework") Cc: stable@vger.kernel.org Signed-off-by: Pali Rohár Link: https://lore.kernel.org/r/20211002130900.9518-1-pali@kernel.org Signed-off-by: Greg Kroah-Hartman

serial: core: fix suspicious security_locked_down() call

2021-06-03T06:59:03Z

commit 5e722b217ad3cf41f5504db80a68062df82b5242 upstream. The commit that added this check did so in a very strange way - first security_locked_down() is called, its value stored into retval, and if it's nonzero, then an additional check is made for (change_irq || change_port), and if this is true, the function returns. However, if the goto exit branch is not taken, the code keeps the retval value and continues executing the function. Then, depending on whether uport->ops->verify_port is set, the retval value may or may not be reset to zero and eventually the error value from security_locked_down() may abort the function a few lines below. I will go out on a limb and assume that this isn't the intended behavior and that an error value from security_locked_down() was supposed to abort the function only in case (change_irq || change_port) is true. Note that security_locked_down() should be called last in any series of checks, since the SELinux implementation of this hook will do a check against the policy and generate an audit record in case of denial. If the operation was to carry on after calling security_locked_down(), then the SELinux denial record would be bogus. See commit 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown") for how SELinux implements this hook. Fixes: 794edf30ee6c ("lockdown: Lock down TIOCSSERIAL") Acked-by: Kees Cook Signed-off-by: Ondrej Mosnacek Cc: stable Link: https://lore.kernel.org/r/20210507115719.140799-1-omosnace@redhat.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

serial: core: return early on unsupported ioctls

2021-05-14T07:44:22Z

[ Upstream commit 79c5966cec7b148199386ef9933c31b999379065 ] Drivers can return -ENOIOCTLCMD when an ioctl is not recognised to tell the upper layers to continue looking for a handler. This is not the case for the RS485 and ISO7816 ioctls whose handlers should return -ENOTTY directly in case a serial driver does not implement the corresponding methods. Fixes: a5f276f10ff7 ("serial_core: Handle TIOC[GS]RS485 ioctls.") Fixes: ad8c0eaa0a41 ("tty/serial_core: add ISO7816 infrastructure") Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210407095208.31838-9-johan@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial_core: Check for port state when tty is in error state

2020-12-30T10:51:00Z

commit 2f70e49ed860020f5abae4f7015018ebc10e1f0e upstream. At the moment opening a serial device node (such as /dev/ttyS3) succeeds even if there is no actual serial device behind it. Reading/writing/ioctls fail as expected because the uart port is not initialized (the type is PORT_UNKNOWN) and the TTY_IO_ERROR error state bit is set fot the tty. However setting line discipline does not have these checks 8250_port.c (8250 is the default choice made by univ8250_console_init()). As the result of PORT_UNKNOWN, uart_port::iobase is NULL which a platform translates onto some address accessing which produces a crash like below. This adds tty_port_initialized() to uart_set_ldisc() to prevent the crash. Found by syzkaller. Signed-off-by: Alexey Kardashevskiy Link: https://lore.kernel.org/r/20201203055834.45838-1-aik@ozlabs.ru Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: link tty and port before configuring it as console

2020-01-14T19:08:33Z

commit fb2b90014d782d80d7ebf663e50f96d8c507a73c upstream. There seems to be a race condition in tty drivers and I could see on many boot cycles a NULL pointer dereference as tty_init_dev() tries to do 'tty->port->itty = tty' even though tty->port is NULL. 'tty->port' will be set by the driver and if the driver has not yet done it before we open the tty device we can get to this situation. By adding some extra debug prints, I noticed that: 6.650130: uart_add_one_port 6.663849: register_console 6.664846: tty_open 6.674391: tty_init_dev 6.675456: tty_port_link_device uart_add_one_port() registers the console, as soon as it registers, the userspace tries to use it and that leads to tty_open() but uart_add_one_port() has not yet done tty_port_link_device() and so tty->port is not yet configured when control reaches tty_init_dev(). Further look into the code and tty_port_link_device() is done by uart_add_one_port(). After registering the console uart_add_one_port() will call tty_port_register_device_attr_serdev() and tty_port_link_device() is called from this. Call add tty_port_link_device() before uart_configure_port() is done and add a check in tty_port_link_device() so that it only links the port if it has not been done yet. Suggested-by: Jiri Slaby Signed-off-by: Sudip Mukherjee Cc: stable Link: https://lore.kernel.org/r/20191212131602.29504-1-sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman

serial: serial_core: Perform NULL checks for break_ctl ops

2019-12-13T07:42:23Z

commit 7d73170e1c282576419f8b50a771f1fcd2b81a94 upstream. Doing fuzz test on sbsa uart device, causes a kernel crash due to NULL pointer dereference: ------------[ cut here ]------------ Unable to handle kernel paging request at virtual address fffffffffffffffc pgd = ffffffe331723000 [fffffffffffffffc] *pgd=0000002333595003, *pud=0000002333595003, *pmd=00000 Internal error: Oops: 96000005 [#1] PREEMPT SMP Modules linked in: ping(O) jffs2 rtos_snapshot(O) pramdisk(O) hisi_sfc(O) Drv_Nandc_K(O) Drv_SysCtl_K(O) Drv_SysClk_K(O) bsp_reg(O) hns3(O) hns3_uio_enet(O) hclgevf(O) hclge(O) hnae3(O) mdio_factory(O) mdio_registry(O) mdio_dev(O) mdio(O) hns3_info(O) rtos_kbox_panic(O) uart_suspend(O) rsm(O) stp llc tunnel4 xt_tcpudp ipt_REJECT nf_reject_ipv4 iptable_filter ip_tables x_tables sd_mod xhci_plat_hcd xhci_pci xhci_hcd usbmon usbhid usb_storage ohci_platform ohci_pci ohci_hcd hid_generic hid ehci_platform ehci_pci ehci_hcd vfat fat usbcore usb_common scsi_mod yaffs2multi(O) ext4 jbd2 ext2 mbcache ofpart i2c_dev i2c_core uio ubi nand nand_ecc nand_ids cfi_cmdset_0002 cfi_cmdset_0001 cfi_probe gen_probe cmdlinepart chipreg mtdblock mtd_blkdevs mtd nfsd auth_rpcgss oid_registry nfsv3 nfs nfs_acl lockd sunrpc grace autofs4 CPU: 2 PID: 2385 Comm: tty_fuzz_test Tainted: G O 4.4.193 #1 task: ffffffe32b23f110 task.stack: ffffffe32bda4000 PC is at uart_break_ctl+0x44/0x84 LR is at uart_break_ctl+0x34/0x84 pc : [] lr : [] pstate: 80000005 sp : ffffffe32bda7cc0 x29: ffffffe32bda7cc0 x28: ffffffe32b23f110 x27: ffffff8393402000 x26: 0000000000000000 x25: ffffffe32b233f40 x24: ffffffc07a8ec680 x23: 0000000000005425 x22: 00000000ffffffff x21: ffffffe33ed73c98 x20: 0000000000000000 x19: ffffffe33ed94168 x18: 0000000000000004 x17: 0000007f92ae9d30 x16: ffffff8392fa6064 x15: 0000000000000010 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000020 x10: 0000007ffdac1708 x9 : 0000000000000078 x8 : 000000000000001d x7 : 0000000052a64887 x6 : ffffffe32bda7e08 x5 : ffffffe32b23c000 x4 : 0000005fbc5b0000 x3 : ffffff83938d5018 x2 : 0000000000000080 x1 : ffffffe32b23c040 x0 : ffffff83934428f8 virtual start addr offset is 38ac00000 module base offset is 2cd4cf1000 linear region base offset is : 0 Process tty_fuzz_test (pid: 2385, stack limit = 0xffffffe32bda4000) Stack: (0xffffffe32bda7cc0 to 0xffffffe32bda8000) 7cc0: ffffffe32bda7cf0 ffffff8393177718 ffffffc07a8ec680 ffffff8393196054 7ce0: 000000001739f2e0 0000007ffdac1978 ffffffe32bda7d20 ffffff8393179a1c 7d00: 0000000000000000 ffffff8393c0a000 ffffffc07a8ec680 cb88537fdc8ba600 7d20: ffffffe32bda7df0 ffffff8392fa5a40 ffffff8393c0a000 0000000000005425 7d40: 0000007ffdac1978 ffffffe32b233f40 ffffff8393178dcc 0000000000000003 7d60: 000000000000011d 000000000000001d ffffffe32b23f110 000000000000029e 7d80: ffffffe34fe8d5d0 0000000000000000 ffffffe32bda7e14 cb88537fdc8ba600 7da0: ffffffe32bda7e30 ffffff8393042cfc ffffff8393c41720 ffffff8393c46410 7dc0: ffffff839304fa68 ffffffe32b233f40 0000000000005425 0000007ffdac1978 7de0: 000000000000011d cb88537fdc8ba600 ffffffe32bda7e70 ffffff8392fa60cc 7e00: 0000000000000000 ffffffe32b233f40 ffffffe32b233f40 0000000000000003 7e20: 0000000000005425 0000007ffdac1978 ffffffe32bda7e70 ffffff8392fa60b0 7e40: 0000000000000280 ffffffe32b233f40 ffffffe32b233f40 0000000000000003 7e60: 0000000000005425 cb88537fdc8ba600 0000000000000000 ffffff8392e02e78 7e80: 0000000000000280 0000005fbc5b0000 ffffffffffffffff 0000007f92ae9d3c 7ea0: 0000000060000000 0000000000000015 0000000000000003 0000000000005425 7ec0: 0000007ffdac1978 0000000000000000 00000000a54c910e 0000007f92b95014 7ee0: 0000007f92b95090 0000000052a64887 000000000000001d 0000000000000078 7f00: 0000007ffdac1708 0000000000000020 0000000000000000 0000000000000000 7f20: 0000000000000000 0000000000000010 000000556acf0090 0000007f92ae9d30 7f40: 0000000000000004 000000556acdef10 0000000000000000 000000556acdebd0 7f60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 7f80: 0000000000000000 0000000000000000 0000000000000000 0000007ffdac1840 7fa0: 000000556acdedcc 0000007ffdac1840 0000007f92ae9d3c 0000000060000000 7fc0: 0000000000000000 0000000000000000 0000000000000003 000000000000001d 7fe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 Call trace: Exception stack(0xffffffe32bda7ab0 to 0xffffffe32bda7bf0) 7aa0: 0000000000001000 0000007fffffffff 7ac0: ffffffe32bda7cc0 ffffff8393196098 0000000080000005 0000000000000025 7ae0: ffffffe32b233f40 ffffff83930d777c ffffffe32bda7b30 ffffff83930d777c 7b00: ffffffe32bda7be0 ffffff83938d5000 ffffffe32bda7be0 ffffffe32bda7c20 7b20: ffffffe32bda7b60 ffffff83930d777c ffffffe32bda7c10 ffffff83938d5000 7b40: ffffffe32bda7c10 ffffffe32bda7c50 ffffff8393c0a000 ffffffe32b23f110 7b60: ffffffe32bda7b70 ffffff8392e09df4 ffffffe32bda7bb0 cb88537fdc8ba600 7b80: ffffff83934428f8 ffffffe32b23c040 0000000000000080 ffffff83938d5018 7ba0: 0000005fbc5b0000 ffffffe32b23c000 ffffffe32bda7e08 0000000052a64887 7bc0: 000000000000001d 0000000000000078 0000007ffdac1708 0000000000000020 7be0: 0000000000000000 0000000000000000 [] uart_break_ctl+0x44/0x84 [] send_break+0xa0/0x114 [] tty_ioctl+0xc50/0xe84 [] do_vfs_ioctl+0xc4/0x6e8 [] SyS_ioctl+0x68/0x9c [] __sys_trace_return+0x0/0x4 Code: b9410ea0 34000160 f9408aa0 f9402814 (b85fc280) ---[ end trace 8606094f1960c5e0 ]--- Kernel panic - not syncing: Fatal exception Fix this problem by adding NULL checks prior to calling break_ctl ops. Signed-off-by: Jiangfeng Xiao Cc: stable Link: https://lore.kernel.org/r/1574263133-28259-1-git-send-email-xiaojiangfeng@huawei.com Signed-off-by: Greg Kroah-Hartman