diff --git a/patch/driver-uart-fix-another-race-between-uart_put_char-and-uart_shutdow.patch b/patch/driver-uart-fix-another-race-between-uart_put_char-and-uart_shutdow.patch new file mode 100644 index 000000000000..204101805e2c --- /dev/null +++ b/patch/driver-uart-fix-another-race-between-uart_put_char-and-uart_shutdow.patch @@ -0,0 +1,28 @@ +uart: fix another race between uart_put_char() and uart_shutdown() + +From: Guohan Lu + +this is complete the fix in a5ba1d95e46ecaea638ddd7cd144107c783acb5d +--- + drivers/tty/serial/serial_core.c | 6 ++++-- + 1 file changed, 4 insertions(+), 2 deletions(-) + +diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c +index 53e6db8..ec1187d 100644 +--- a/drivers/tty/serial/serial_core.c ++++ b/drivers/tty/serial/serial_core.c +@@ -530,10 +530,12 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c) + int ret = 0; + + circ = &state->xmit; +- if (!circ->buf) ++ port = uart_port_lock(state, flags); ++ if (!circ->buf) { ++ uart_port_unlock(port, flags); + return 0; ++ } + +- port = uart_port_lock(state, flags); + if (port && uart_circ_chars_free(circ) != 0) { + circ->buf[circ->head] = c; + circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1); diff --git a/patch/driver-uart-fix-race-between-uart_put_char-and-uart_shutdow.patch b/patch/driver-uart-fix-race-between-uart_put_char-and-uart_shutdow.patch new file mode 100644 index 000000000000..793014aecaac --- /dev/null +++ b/patch/driver-uart-fix-race-between-uart_put_char-and-uart_shutdow.patch @@ -0,0 +1,186 @@ +From a5ba1d95e46ecaea638ddd7cd144107c783acb5d Mon Sep 17 00:00:00 2001 +From: Tycho Andersen +Date: Fri, 6 Jul 2018 10:24:57 -0600 +Subject: [PATCH] uart: fix race between uart_put_char() and uart_shutdown() +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +We have reports of the following crash: + + PID: 7 TASK: ffff88085c6d61c0 CPU: 1 COMMAND: "kworker/u25:0" + #0 [ffff88085c6db710] machine_kexec at ffffffff81046239 + #1 [ffff88085c6db760] crash_kexec at ffffffff810fc248 + #2 [ffff88085c6db830] oops_end at ffffffff81008ae7 + #3 [ffff88085c6db860] no_context at ffffffff81050b8f + #4 [ffff88085c6db8b0] __bad_area_nosemaphore at ffffffff81050d75 + #5 [ffff88085c6db900] bad_area_nosemaphore at ffffffff81050e83 + #6 [ffff88085c6db910] __do_page_fault at ffffffff8105132e + #7 [ffff88085c6db9b0] do_page_fault at ffffffff8105152c + #8 [ffff88085c6db9c0] page_fault at ffffffff81a3f122 + [exception RIP: uart_put_char+149] + RIP: ffffffff814b67b5 RSP: ffff88085c6dba78 RFLAGS: 00010006 + RAX: 0000000000000292 RBX: ffffffff827c5120 RCX: 0000000000000081 + RDX: 0000000000000000 RSI: 000000000000005f RDI: ffffffff827c5120 + RBP: ffff88085c6dba98 R8: 000000000000012c R9: ffffffff822ea320 + R10: ffff88085fe4db04 R11: 0000000000000001 R12: ffff881059f9c000 + R13: 0000000000000001 R14: 000000000000005f R15: 0000000000000fba + ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 + #9 [ffff88085c6dbaa0] tty_put_char at ffffffff81497544 + #10 [ffff88085c6dbac0] do_output_char at ffffffff8149c91c + #11 [ffff88085c6dbae0] __process_echoes at ffffffff8149cb8b + #12 [ffff88085c6dbb30] commit_echoes at ffffffff8149cdc2 + #13 [ffff88085c6dbb60] n_tty_receive_buf_fast at ffffffff8149e49b + #14 [ffff88085c6dbbc0] __receive_buf at ffffffff8149ef5a + #15 [ffff88085c6dbc20] n_tty_receive_buf_common at ffffffff8149f016 + #16 [ffff88085c6dbca0] n_tty_receive_buf2 at ffffffff8149f194 + #17 [ffff88085c6dbcb0] flush_to_ldisc at ffffffff814a238a + #18 [ffff88085c6dbd50] process_one_work at ffffffff81090be2 + #19 [ffff88085c6dbe20] worker_thread at ffffffff81091b4d + #20 [ffff88085c6dbeb0] kthread at ffffffff81096384 + #21 [ffff88085c6dbf50] ret_from_fork at ffffffff81a3d69f​ + +after slogging through some dissasembly: + +ffffffff814b6720 : +ffffffff814b6720: 55 push %rbp +ffffffff814b6721: 48 89 e5 mov %rsp,%rbp +ffffffff814b6724: 48 83 ec 20 sub $0x20,%rsp +ffffffff814b6728: 48 89 1c 24 mov %rbx,(%rsp) +ffffffff814b672c: 4c 89 64 24 08 mov %r12,0x8(%rsp) +ffffffff814b6731: 4c 89 6c 24 10 mov %r13,0x10(%rsp) +ffffffff814b6736: 4c 89 74 24 18 mov %r14,0x18(%rsp) +ffffffff814b673b: e8 b0 8e 58 00 callq ffffffff81a3f5f0 +ffffffff814b6740: 4c 8b a7 88 02 00 00 mov 0x288(%rdi),%r12 +ffffffff814b6747: 45 31 ed xor %r13d,%r13d +ffffffff814b674a: 41 89 f6 mov %esi,%r14d +ffffffff814b674d: 49 83 bc 24 70 01 00 cmpq $0x0,0x170(%r12) +ffffffff814b6754: 00 00 +ffffffff814b6756: 49 8b 9c 24 80 01 00 mov 0x180(%r12),%rbx +ffffffff814b675d: 00 +ffffffff814b675e: 74 2f je ffffffff814b678f +ffffffff814b6760: 48 89 df mov %rbx,%rdi +ffffffff814b6763: e8 a8 67 58 00 callq ffffffff81a3cf10 <_raw_spin_lock_irqsave> +ffffffff814b6768: 41 8b 8c 24 78 01 00 mov 0x178(%r12),%ecx +ffffffff814b676f: 00 +ffffffff814b6770: 89 ca mov %ecx,%edx +ffffffff814b6772: f7 d2 not %edx +ffffffff814b6774: 41 03 94 24 7c 01 00 add 0x17c(%r12),%edx +ffffffff814b677b: 00 +ffffffff814b677c: 81 e2 ff 0f 00 00 and $0xfff,%edx +ffffffff814b6782: 75 23 jne ffffffff814b67a7 +ffffffff814b6784: 48 89 c6 mov %rax,%rsi +ffffffff814b6787: 48 89 df mov %rbx,%rdi +ffffffff814b678a: e8 e1 64 58 00 callq ffffffff81a3cc70 <_raw_spin_unlock_irqrestore> +ffffffff814b678f: 44 89 e8 mov %r13d,%eax +ffffffff814b6792: 48 8b 1c 24 mov (%rsp),%rbx +ffffffff814b6796: 4c 8b 64 24 08 mov 0x8(%rsp),%r12 +ffffffff814b679b: 4c 8b 6c 24 10 mov 0x10(%rsp),%r13 +ffffffff814b67a0: 4c 8b 74 24 18 mov 0x18(%rsp),%r14 +ffffffff814b67a5: c9 leaveq +ffffffff814b67a6: c3 retq +ffffffff814b67a7: 49 8b 94 24 70 01 00 mov 0x170(%r12),%rdx +ffffffff814b67ae: 00 +ffffffff814b67af: 48 63 c9 movslq %ecx,%rcx +ffffffff814b67b2: 41 b5 01 mov $0x1,%r13b +ffffffff814b67b5: 44 88 34 0a mov %r14b,(%rdx,%rcx,1) +ffffffff814b67b9: 41 8b 94 24 78 01 00 mov 0x178(%r12),%edx +ffffffff814b67c0: 00 +ffffffff814b67c1: 83 c2 01 add $0x1,%edx +ffffffff814b67c4: 81 e2 ff 0f 00 00 and $0xfff,%edx +ffffffff814b67ca: 41 89 94 24 78 01 00 mov %edx,0x178(%r12) +ffffffff814b67d1: 00 +ffffffff814b67d2: eb b0 jmp ffffffff814b6784 +ffffffff814b67d4: 66 66 66 2e 0f 1f 84 data32 data32 nopw %cs:0x0(%rax,%rax,1) +ffffffff814b67db: 00 00 00 00 00 + +for our build, this is crashing at: + + circ->buf[circ->head] = c; + +Looking in uart_port_startup(), it seems that circ->buf (state->xmit.buf) +protected by the "per-port mutex", which based on uart_port_check() is +state->port.mutex. Indeed, the lock acquired in uart_put_char() is +uport->lock, i.e. not the same lock. + +Anyway, since the lock is not acquired, if uart_shutdown() is called, the +last chunk of that function may release state->xmit.buf before its assigned +to null, and cause the race above. + +To fix it, let's lock uport->lock when allocating/deallocating +state->xmit.buf in addition to the per-port mutex. + +v2: switch to locking uport->lock on allocation/deallocation instead of + locking the per-port mutex in uart_put_char. Note that since + uport->lock is a spin lock, we have to switch the allocation to + GFP_ATOMIC. +v3: move the allocation outside the lock, so we can switch back to + GFP_KERNEL + +Signed-off-by: Tycho Andersen +Cc: stable +Signed-off-by: Greg Kroah-Hartman +--- + drivers/tty/serial/serial_core.c | 17 ++++++++++++----- + 1 file changed, 12 insertions(+), 5 deletions(-) + +diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c +index 9c14a45..80bb56f 100644 +--- a/drivers/tty/serial/serial_core.c ++++ b/drivers/tty/serial/serial_core.c +@@ -182,6 +182,7 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, + { + struct uart_port *uport = uart_port_check(state); + unsigned long page; ++ unsigned long flags = 0; + int retval = 0; + + if (uport->type == PORT_UNKNOWN) +@@ -196,15 +197,18 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, + * Initialise and allocate the transmit and temporary + * buffer. + */ +- if (!state->xmit.buf) { +- /* This is protected by the per port mutex */ +- page = get_zeroed_page(GFP_KERNEL); +- if (!page) +- return -ENOMEM; ++ page = get_zeroed_page(GFP_KERNEL); ++ if (!page) ++ return -ENOMEM; + ++ uart_port_lock(state, flags); ++ if (!state->xmit.buf) { + state->xmit.buf = (unsigned char *) page; + uart_circ_clear(&state->xmit); ++ } else { ++ free_page(page); + } ++ uart_port_unlock(uport, flags); + + retval = uport->ops->startup(uport); + if (retval == 0) { +@@ -263,6 +267,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) + { + struct uart_port *uport = uart_port_check(state); + struct tty_port *port = &state->port; ++ unsigned long flags = 0; + + /* + * Set the TTY IO error marker +@@ -295,10 +300,12 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state) + /* + * Free the transmit buffer page. + */ ++ uart_port_lock(state, flags); + if (state->xmit.buf) { + free_page((unsigned long)state->xmit.buf); + state->xmit.buf = NULL; + } ++ uart_port_unlock(uport, flags); + } + + /** +-- +2.7.4 + diff --git a/patch/series b/patch/series index 5c1dbdf10bc5..3608593ca4e3 100644 --- a/patch/series +++ b/patch/series @@ -21,6 +21,8 @@ driver-sff-8436-use-nvmem-framework.patch driver-sff-8436-use-nvmem_device_read.patch driver-support-sff-8436-read-write-fix.patch driver-i2c-bus-intel-ismt-add-delay-param.patch +driver-uart-fix-race-between-uart_put_char-and-uart_shutdow.patch +driver-uart-fix-another-race-between-uart_put_char-and-uart_shutdow.patch driver-pca954x-i2c-mux-force-deselect-on-exit-flag.patch kernel-add-kexec-reboot-string.patch driver-hwmon-max6620.patch