May 2022 - Linux-stable-mirror

FAILED: patch "[PATCH] tty: n_gsm: fix reset fifo race condition" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 73029a4d7161f8b6c0934553145ef574d2d0c645 Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:22 -0700 Subject: [PATCH] tty: n_gsm: fix reset fifo race condition gsmtty_write() and gsm_dlci_data_output() properly guard the fifo access. However, gsm_dlci_close() and gsmtty_flush_buffer() modifies the fifo but do not guard this. Add a guard here to prevent race conditions on parallel writes to the fifo. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-17-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index f3fb66be8513..15be4a235783 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1442,13 +1442,17 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control) static void gsm_dlci_close(struct gsm_dlci *dlci) { + unsigned long flags; + del_timer(&dlci->t1); if (debug & 8) pr_debug("DLCI %d goes closed.\n", dlci->addr); dlci->state = DLCI_CLOSED; if (dlci->addr != 0) { tty_port_tty_hangup(&dlci->port, false); + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Ensure that gsmtty_open() can return. */ tty_port_set_initialized(&dlci->port, 0); wake_up_interruptible(&dlci->port.open_wait); @@ -3148,13 +3152,17 @@ static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) static void gsmtty_flush_buffer(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; + unsigned long flags; + if (dlci->state == DLCI_CLOSED) return; /* Caution needed: If we implement reliable transport classes then the data being transmitted can't simply be junked once it has first hit the stack. Until then we can just blow it away */ + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Need to unhook this DLCI from the transmit queue logic */ }

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix reset fifo race condition" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 73029a4d7161f8b6c0934553145ef574d2d0c645 Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:22 -0700 Subject: [PATCH] tty: n_gsm: fix reset fifo race condition gsmtty_write() and gsm_dlci_data_output() properly guard the fifo access. However, gsm_dlci_close() and gsmtty_flush_buffer() modifies the fifo but do not guard this. Add a guard here to prevent race conditions on parallel writes to the fifo. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-17-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index f3fb66be8513..15be4a235783 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1442,13 +1442,17 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control) static void gsm_dlci_close(struct gsm_dlci *dlci) { + unsigned long flags; + del_timer(&dlci->t1); if (debug & 8) pr_debug("DLCI %d goes closed.\n", dlci->addr); dlci->state = DLCI_CLOSED; if (dlci->addr != 0) { tty_port_tty_hangup(&dlci->port, false); + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Ensure that gsmtty_open() can return. */ tty_port_set_initialized(&dlci->port, 0); wake_up_interruptible(&dlci->port.open_wait); @@ -3148,13 +3152,17 @@ static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) static void gsmtty_flush_buffer(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; + unsigned long flags; + if (dlci->state == DLCI_CLOSED) return; /* Caution needed: If we implement reliable transport classes then the data being transmitted can't simply be junked once it has first hit the stack. Until then we can just blow it away */ + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Need to unhook this DLCI from the transmit queue logic */ }

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:19 -0700 Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type 2 gsm_control_modem() informs the virtual tty that more data can be written after receiving a control signal octet via modem status command (MSC). However, gsm_dlci_data() fails to do the same after receiving a control signal octet from the convergence layer type 2 header. Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23418ee93156..f3fb66be8513 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:19 -0700 Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type 2 gsm_control_modem() informs the virtual tty that more data can be written after receiving a control signal octet via modem status command (MSC). However, gsm_dlci_data() fails to do the same after receiving a control signal octet from the convergence layer type 2 header. Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23418ee93156..f3fb66be8513 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:19 -0700 Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type 2 gsm_control_modem() informs the virtual tty that more data can be written after receiving a control signal octet via modem status command (MSC). However, gsm_dlci_data() fails to do the same after receiving a control signal octet from the convergence layer type 2 header. Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23418ee93156..f3fb66be8513 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:19 -0700 Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type 2 gsm_control_modem() informs the virtual tty that more data can be written after receiving a control signal octet via modem status command (MSC). However, gsm_dlci_data() fails to do the same after receiving a control signal octet from the convergence layer type 2 header. Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23418ee93156..f3fb66be8513 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 1adf6fee58ca25fb6720b8d34c919dcf5425cc9c Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:19 -0700 Subject: [PATCH] tty: n_gsm: fix missing tty wakeup in convergence layer type 2 gsm_control_modem() informs the virtual tty that more data can be written after receiving a control signal octet via modem status command (MSC). However, gsm_dlci_data() fails to do the same after receiving a control signal octet from the convergence layer type 2 header. Add tty_wakeup() in gsm_dlci_data() for convergence layer type 2 to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-14-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23418ee93156..f3fb66be8513 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1615,6 +1615,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) tty = tty_port_tty_get(port); if (tty) { gsm_process_modem(tty, dlci, modem, slen); + tty_wakeup(tty); tty_kref_put(tty); } fallthrough;

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 317f86af7f5d19f286ed2d181cbaef4a188c7f19 Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:18 -0700 Subject: [PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC 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.… The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. The value of the modem status command (MSC) frame contains an address field, control signal and optional break signal octet. The address field is encoded as described in chapter 5.2.1.2 with only one octet (may be extended to more in future versions of the standard). Whereas the control signal and break signal octet are always one byte each. This is strange at first glance as it makes the EA bit redundant. However, the same two octets are also encoded as header in convergence layer type 2 as described in chapter 5.5.2. No header length field is given and the only way to test if there is an optional break signal octet is via the EA flag which extends the control signal octet with a break signal octet. Now it becomes obvious how the EA bit for those two octets shall be encoded in the MSC frame. The current implementation treats the signal octet different for MSC frame and convergence layer type 2 header even though the standard describes it for both in the same way. Use the EA bit to encode the signal octets not only in the convergence layer type 2 header but also in the MSC frame in the same way with either 1 or 2 bytes in case of an optional break signal. Adjust the receiving path accordingly in gsm_control_modem(). Fixes: 3ac06b905655 ("tty: n_gsm: Fix for modems with brk in modem status control") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-13-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 903278145078..23418ee93156 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1094,7 +1094,6 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) { unsigned int addr = 0; unsigned int modem = 0; - unsigned int brk = 0; struct gsm_dlci *dlci; int len = clen; int slen; @@ -1124,17 +1123,8 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) return; } len--; - if (len > 0) { - while (gsm_read_ea(&brk, *dp++) == 0) { - len--; - if (len == 0) - return; - } - modem <<= 7; - modem |= (brk & 0x7f); - } tty = tty_port_tty_get(&dlci->port); - gsm_process_modem(tty, dlci, modem, slen); + gsm_process_modem(tty, dlci, modem, slen - len); if (tty) { tty_wakeup(tty); tty_kref_put(tty); @@ -2963,8 +2953,10 @@ static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk) int len = 2; modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */ - modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; - if (brk) { + if (!brk) { + modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; + } else { + modembits[1] = gsm_encode_modem(dlci) << 1; modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */ len++; }

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 317f86af7f5d19f286ed2d181cbaef4a188c7f19 Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:18 -0700 Subject: [PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC 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.… The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. The value of the modem status command (MSC) frame contains an address field, control signal and optional break signal octet. The address field is encoded as described in chapter 5.2.1.2 with only one octet (may be extended to more in future versions of the standard). Whereas the control signal and break signal octet are always one byte each. This is strange at first glance as it makes the EA bit redundant. However, the same two octets are also encoded as header in convergence layer type 2 as described in chapter 5.5.2. No header length field is given and the only way to test if there is an optional break signal octet is via the EA flag which extends the control signal octet with a break signal octet. Now it becomes obvious how the EA bit for those two octets shall be encoded in the MSC frame. The current implementation treats the signal octet different for MSC frame and convergence layer type 2 header even though the standard describes it for both in the same way. Use the EA bit to encode the signal octets not only in the convergence layer type 2 header but also in the MSC frame in the same way with either 1 or 2 bytes in case of an optional break signal. Adjust the receiving path accordingly in gsm_control_modem(). Fixes: 3ac06b905655 ("tty: n_gsm: Fix for modems with brk in modem status control") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-13-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 903278145078..23418ee93156 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1094,7 +1094,6 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) { unsigned int addr = 0; unsigned int modem = 0; - unsigned int brk = 0; struct gsm_dlci *dlci; int len = clen; int slen; @@ -1124,17 +1123,8 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) return; } len--; - if (len > 0) { - while (gsm_read_ea(&brk, *dp++) == 0) { - len--; - if (len == 0) - return; - } - modem <<= 7; - modem |= (brk & 0x7f); - } tty = tty_port_tty_get(&dlci->port); - gsm_process_modem(tty, dlci, modem, slen); + gsm_process_modem(tty, dlci, modem, slen - len); if (tty) { tty_wakeup(tty); tty_kref_put(tty); @@ -2963,8 +2953,10 @@ static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk) int len = 2; modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */ - modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; - if (brk) { + if (!brk) { + modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; + } else { + modembits[1] = gsm_encode_modem(dlci) << 1; modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */ len++; }

2 years, 8 months

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FAILED: patch "[PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 317f86af7f5d19f286ed2d181cbaef4a188c7f19 Mon Sep 17 00:00:00 2001 From: Daniel Starke <daniel.starke(a)siemens.com> Date: Thu, 14 Apr 2022 02:42:18 -0700 Subject: [PATCH] tty: n_gsm: fix wrong signal octets encoding in MSC 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.… The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. The value of the modem status command (MSC) frame contains an address field, control signal and optional break signal octet. The address field is encoded as described in chapter 5.2.1.2 with only one octet (may be extended to more in future versions of the standard). Whereas the control signal and break signal octet are always one byte each. This is strange at first glance as it makes the EA bit redundant. However, the same two octets are also encoded as header in convergence layer type 2 as described in chapter 5.5.2. No header length field is given and the only way to test if there is an optional break signal octet is via the EA flag which extends the control signal octet with a break signal octet. Now it becomes obvious how the EA bit for those two octets shall be encoded in the MSC frame. The current implementation treats the signal octet different for MSC frame and convergence layer type 2 header even though the standard describes it for both in the same way. Use the EA bit to encode the signal octets not only in the convergence layer type 2 header but also in the MSC frame in the same way with either 1 or 2 bytes in case of an optional break signal. Adjust the receiving path accordingly in gsm_control_modem(). Fixes: 3ac06b905655 ("tty: n_gsm: Fix for modems with brk in modem status control") Cc: stable(a)vger.kernel.org Signed-off-by: Daniel Starke <daniel.starke(a)siemens.com> Link: https://lore.kernel.org/r/20220414094225.4527-13-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 903278145078..23418ee93156 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1094,7 +1094,6 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) { unsigned int addr = 0; unsigned int modem = 0; - unsigned int brk = 0; struct gsm_dlci *dlci; int len = clen; int slen; @@ -1124,17 +1123,8 @@ static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen) return; } len--; - if (len > 0) { - while (gsm_read_ea(&brk, *dp++) == 0) { - len--; - if (len == 0) - return; - } - modem <<= 7; - modem |= (brk & 0x7f); - } tty = tty_port_tty_get(&dlci->port); - gsm_process_modem(tty, dlci, modem, slen); + gsm_process_modem(tty, dlci, modem, slen - len); if (tty) { tty_wakeup(tty); tty_kref_put(tty); @@ -2963,8 +2953,10 @@ static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk) int len = 2; modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */ - modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; - if (brk) { + if (!brk) { + modembits[1] = (gsm_encode_modem(dlci) << 1) | EA; + } else { + modembits[1] = gsm_encode_modem(dlci) << 1; modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */ len++; }

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Linux-stable-mirror May 2022