commit 7c0cca7c847e6e019d67b7d793efbbe3b947d004 upstream. By default, the kernel will automatically load the module of any line dicipline that is asked for. As this sometimes isn't the safest thing to do, provide a sysctl to disable this feature. By default, we set this to 'y' as that is the historical way that Linux has worked, and we do not want to break working systems. But in the future, perhaps this can default to 'n' to prevent this functionality. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 27cfb3a53be46a54ec5e0bd04e51995b74c90343 upstream. Some tty line disciplines do not have a receive buf callback, so properly check for that before calling it. If they do not have this callback, just eat the character quietly, as we can't fail this call. Reported-by: Jann Horn <jannh@google.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 33a1a7be198657c8ca26ad406c4d2a89b7162bcc ] The issue is found by a fuzzing test. If tty_find_polling_driver() recevies an incorrect input such as ',,' or '0b', the len becomes 0 and strncmp() always return 0. In this case, a null p->ops->poll_init() is called and it causes a kernel panic. Fix this by checking name length against zero in tty_find_polling_driver(). $echo ,, > /sys/module/kgdboc/parameters/kgdboc [ 20.804451] WARNING: CPU: 1 PID: 104 at drivers/tty/serial/serial_core.c:457 uart_get_baud_rate+0xe8/0x190 [ 20.804917] Modules linked in: [ 20.805317] CPU: 1 PID: 104 Comm: sh Not tainted 4.19.0-rc7ajb #8 [ 20.805469] Hardware name: linux,dummy-virt (DT) [ 20.805732] pstate: 20000005 (nzCv daif -PAN -UAO) [ 20.805895] pc : uart_get_baud_rate+0xe8/0x190 [ 20.806042] lr : uart_get_baud_rate+0xc0/0x190 [ 20.806476] sp : ffffffc06acff940 [ 20.806676] x29: ffffffc06acff940 x28: 0000000000002580 [ 20.806977] x27: 0000000000009600 x26: 0000000000009600 [ 20.807231] x25: ffffffc06acffad0 x24: 00000000ffffeff0 [ 20.807576] x23: 0000000000000001 x22: 0000000000000000 [ 20.807807] x21: 0000000000000001 x20: 0000000000000000 [ 20.808049] x19: ffffffc06acffac8 x18: 0000000000000000 [ 20.808277] x17: 0000000000000000 x16: 0000000000000000 [ 20.808520] x15: ffffffffffffffff x14: ffffffff00000000 [ 20.808757] x13: ffffffffffffffff x12: 0000000000000001 [ 20.809011] x11: 0101010101010101 x10: ffffff880d59ff5f [ 20.809292] x9 : ffffff880d59ff5e x8 : ffffffc06acffaf3 [ 20.809549] x7 : 0000000000000000 x6 : ffffff880d59ff5f [ 20.809803] x5 : 0000000080008001 x4 : 0000000000000003 [ 20.810056] x3 : ffffff900853e6b4 x2 : dfffff9000000000 [ 20.810693] x1 : ffffffc06acffad0 x0 : 0000000000000cb0 [ 20.811005] Call trace: [ 20.811214] uart_get_baud_rate+0xe8/0x190 [ 20.811479] serial8250_do_set_termios+0xe0/0x6f4 [ 20.811719] serial8250_set_termios+0x48/0x54 [ 20.811928] uart_set_options+0x138/0x1bc [ 20.812129] uart_poll_init+0x114/0x16c [ 20.812330] tty_find_polling_driver+0x158/0x200 [ 20.812545] configure_kgdboc+0xbc/0x1bc [ 20.812745] param_set_kgdboc_var+0xb8/0x150 [ 20.812960] param_attr_store+0xbc/0x150 [ 20.813160] module_attr_store+0x40/0x58 [ 20.813364] sysfs_kf_write+0x8c/0xa8 [ 20.813563] kernfs_fop_write+0x154/0x290 [ 20.813764] vfs_write+0xf0/0x278 [ 20.813951] __arm64_sys_write+0x84/0xf4 [ 20.814400] el0_svc_common+0xf4/0x1dc [ 20.814616] el0_svc_handler+0x98/0xbc [ 20.814804] el0_svc+0x8/0xc [ 20.822005] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 20.826913] Mem abort info: [ 20.827103] ESR = 0x84000006 [ 20.827352] Exception class = IABT (current EL), IL = 16 bits [ 20.827655] SET = 0, FnV = 0 [ 20.827855] EA = 0, S1PTW = 0 [ 20.828135] user pgtable: 4k pages, 39-bit VAs, pgdp = (____ptrval____) [ 20.828484] [0000000000000000] pgd=00000000aadee003, pud=00000000aadee003, pmd=0000000000000000 [ 20.829195] Internal error: Oops: 84000006 [#1] SMP [ 20.829564] Modules linked in: [ 20.829890] CPU: 1 PID: 104 Comm: sh Tainted: G W 4.19.0-rc7ajb #8 [ 20.830545] Hardware name: linux,dummy-virt (DT) [ 20.830829] pstate: 60000085 (nZCv daIf -PAN -UAO) [ 20.831174] pc : (null) [ 20.831457] lr : serial8250_do_set_termios+0x358/0x6f4 [ 20.831727] sp : ffffffc06acff9b0 [ 20.831936] x29: ffffffc06acff9b0 x28: ffffff9008d7c000 [ 20.832267] x27: ffffff900969e16f x26: 0000000000000000 [ 20.832589] x25: ffffff900969dfb0 x24: 0000000000000000 [ 20.832906] x23: ffffffc06acffad0 x22: ffffff900969e160 [ 20.833232] x21: 0000000000000000 x20: ffffffc06acffac8 [ 20.833559] x19: ffffff900969df90 x18: 0000000000000000 [ 20.833878] x17: 0000000000000000 x16: 0000000000000000 [ 20.834491] x15: ffffffffffffffff x14: ffffffff00000000 [ 20.834821] x13: ffffffffffffffff x12: 0000000000000001 [ 20.835143] x11: 0101010101010101 x10: ffffff880d59ff5f [ 20.835467] x9 : ffffff880d59ff5e x8 : ffffffc06acffaf3 [ 20.835790] x7 : 0000000000000000 x6 : ffffff880d59ff5f [ 20.836111] x5 : c06419717c314100 x4 : 0000000000000007 [ 20.836419] x3 : 0000000000000000 x2 : 0000000000000000 [ 20.836732] x1 : 0000000000000001 x0 : ffffff900969df90 [ 20.837100] Process sh (pid: 104, stack limit = 0x(____ptrval____)) [ 20.837396] Call trace: [ 20.837566] (null) [ 20.837816] serial8250_set_termios+0x48/0x54 [ 20.838089] uart_set_options+0x138/0x1bc [ 20.838570] uart_poll_init+0x114/0x16c [ 20.838834] tty_find_polling_driver+0x158/0x200 [ 20.839119] configure_kgdboc+0xbc/0x1bc [ 20.839380] param_set_kgdboc_var+0xb8/0x150 [ 20.839658] param_attr_store+0xbc/0x150 [ 20.839920] module_attr_store+0x40/0x58 [ 20.840183] sysfs_kf_write+0x8c/0xa8 [ 20.840183] sysfs_kf_write+0x8c/0xa8 [ 20.840440] kernfs_fop_write+0x154/0x290 [ 20.840702] vfs_write+0xf0/0x278 [ 20.840942] __arm64_sys_write+0x84/0xf4 [ 20.841209] el0_svc_common+0xf4/0x1dc [ 20.841471] el0_svc_handler+0x98/0xbc [ 20.841713] el0_svc+0x8/0xc [ 20.842057] Code: bad PC value [ 20.842764] ---[ end trace a8835d7de79aaadf ]--- [ 20.843134] Kernel panic - not syncing: Fatal exception [ 20.843515] SMP: stopping secondary CPUs [ 20.844289] Kernel Offset: disabled [ 20.844634] CPU features: 0x0,21806002 [ 20.844857] Memory Limit: none [ 20.845172] ---[ end Kernel panic - not syncing: Fatal exception ]--- Signed-off-by: Miles Chen <miles.chen@mediatek.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 5c17c861a357e9458001f021a7afa7aab9937439 ] ioctl(TIOCGETD) retrieves the line discipline id directly from the ldisc because the line discipline id (c_line) in termios is untrustworthy; userspace may have set termios via ioctl(TCSETS*) without actually changing the line discipline via ioctl(TIOCSETD). However, directly accessing the current ldisc via tty->ldisc is unsafe; the ldisc ptr dereferenced may be stale if the line discipline is changing via ioctl(TIOCSETD) or hangup. Wait for the line discipline reference (just like read() or write()) to retrieve the "current" line discipline id. Cc: <stable@vger.kernel.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
commit f0bf0bd07943bfde8f5ac39a32664810a379c7d3 upstream. This problem was taken care of three times already in * b0de59b5733d18b0d1974a060860a8b5c1b36a2e (TTY: do not update atime/mtime on read/write), * 37b7f3c76595e23257f61bd80b223de8658617ee (TTY: fix atime/mtime regression), and * b0b885657b6c8ef63a46bc9299b2a7715d19acde (tty: fix up atime/mtime mess, take three) But it still misses one point. As John Paul correctly points out, we do not care about setting date. If somebody ever changes wall time backwards (by mistake for example), tty timestamps are never updated until the original wall time passes. So check the absolute difference of times and if it large than "8 seconds or so", always update the time. That means we will update immediatelly when changing time. Ergo, CAP_SYS_TIME can foul the check, but it was always that way. Thanks John for serving me this so nicely debugged. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reported-by: John Paul Perry <john_paul.perry@alcatel-lucent.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Only print one warning when a task is on the read_wait or write_wait wait queue at final tty release. Cc: <stable@vger.kernel.org> # 3.4.x+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Kernel oops can cause the tty to be unreleaseable (for example, if n_tty_read() crashes while on the read_wait queue). This will cause tty_release() to endlessly loop without sleeping. Use a killable sleep timeout which grows by 2n+1 jiffies over the interval [0, 120 secs.) and then jumps to forever (but still killable). NB: killable just allows for the task to be rewoken manually, not to be terminated. Cc: <stable@vger.kernel.org> # since before 2.6.32 Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull file locking related changes from Jeff Layton:
"This release is a little more busy for file locking changes than the
last:
- a set of patches from Kinglong Mee to fix the lockowner handling in
knfsd
- a pile of cleanups to the internal file lease API. This should get
us a bit closer to allowing for setlease methods that can block.
There are some dependencies between mine and Bruce's trees this cycle,
and I based my tree on top of the requisite patches in Bruce's tree"
* tag 'locks-v3.18-1' of git://git.samba.org/jlayton/linux: (26 commits)
locks: fix fcntl_setlease/getlease return when !CONFIG_FILE_LOCKING
locks: flock_make_lock should return a struct file_lock (or PTR_ERR)
locks: set fl_owner for leases to filp instead of current->files
locks: give lm_break a return value
locks: __break_lease cleanup in preparation of allowing direct removal of leases
locks: remove i_have_this_lease check from __break_lease
locks: move freeing of leases outside of i_lock
locks: move i_lock acquisition into generic_*_lease handlers
locks: define a lm_setup handler for leases
locks: plumb a "priv" pointer into the setlease routines
nfsd: don't keep a pointer to the lease in nfs4_file
locks: clean up vfs_setlease kerneldoc comments
locks: generic_delete_lease doesn't need a file_lock at all
nfsd: fix potential lease memory leak in nfs4_setlease
locks: close potential race in lease_get_mtime
security: make security_file_set_fowner, f_setown and __f_setown void return
locks: consolidate "nolease" routines
locks: remove lock_may_read and lock_may_write
lockd: rip out deferred lock handling from testlock codepath
NFSD: Get reference of lockowner when coping file_lock
...
Relocate the file-scope function, send_prio_char(), as a global helper tty_send_xchar(). Remove the global declarations for tty_write_lock()/tty_write_unlock(), as these are file-scope only now. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a master pty is set to packet mode, flow control changes to the slave pty cause notifications to the master pty via reads and polls. However, these tests are occurring for all ttys, not just ptys. Implement flow control packet mode notifications in the pty driver. Only the slave side implements the flow control handlers since packet mode is asymmetric; the master pty receives notifications for slave-side changes, but not vice versa. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>