<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/tty, branch v6.9.4</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>serial: sh-sci: protect invalidating RXDMA on shutdown</title>
<updated>2024-06-12T09:39:21+00:00</updated>
<author>
<name>Wolfram Sang</name>
<email>wsa+renesas@sang-engineering.com</email>
</author>
<published>2024-05-06T11:40:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5172196474c25ec716ebac069e93bfa3bcf3015c'/>
<id>5172196474c25ec716ebac069e93bfa3bcf3015c</id>
<content type='text'>
[ Upstream commit aae20f6e34cd0cbd67a1d0e5877561c40109a81b ]

The to-be-fixed commit removed locking when invalidating the DMA RX
descriptors on shutdown. It overlooked that there is still a rx_timer
running which may still access the protected data. So, re-add the
locking.

Reported-by: Dirk Behme &lt;dirk.behme@de.bosch.com&gt;
Closes: https://lore.kernel.org/r/ee6c9e16-9f29-450e-81da-4a8dceaa8fc7@de.bosch.com
Fixes: 2c4ee23530ff ("serial: sh-sci: Postpone DMA release when falling back to PIO")
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
Link: https://lore.kernel.org/r/20240506114016.30498-7-wsa+renesas@sang-engineering.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit aae20f6e34cd0cbd67a1d0e5877561c40109a81b ]

The to-be-fixed commit removed locking when invalidating the DMA RX
descriptors on shutdown. It overlooked that there is still a rx_timer
running which may still access the protected data. So, re-add the
locking.

Reported-by: Dirk Behme &lt;dirk.behme@de.bosch.com&gt;
Closes: https://lore.kernel.org/r/ee6c9e16-9f29-450e-81da-4a8dceaa8fc7@de.bosch.com
Fixes: 2c4ee23530ff ("serial: sh-sci: Postpone DMA release when falling back to PIO")
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
Link: https://lore.kernel.org/r/20240506114016.30498-7-wsa+renesas@sang-engineering.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: sc16is7xx: add proper sched.h include for sched_set_fifo()</title>
<updated>2024-06-12T09:39:09+00:00</updated>
<author>
<name>Hugo Villeneuve</name>
<email>hvilleneuve@dimonoff.com</email>
</author>
<published>2024-04-09T15:42:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=312a665650024a59239b623e2debd7a9e5df83ef'/>
<id>312a665650024a59239b623e2debd7a9e5df83ef</id>
<content type='text'>
[ Upstream commit 2a8e4ab0c93fad30769479f86849e22d63cd0e12 ]

Replace incorrect include with the proper one for sched_set_fifo()
declaration.

Fixes: 28d2f209cd16 ("sched,serial: Convert to sched_set_fifo()")
Signed-off-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Link: https://lore.kernel.org/r/20240409154253.3043822-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 2a8e4ab0c93fad30769479f86849e22d63cd0e12 ]

Replace incorrect include with the proper one for sched_set_fifo()
declaration.

Fixes: 28d2f209cd16 ("sched,serial: Convert to sched_set_fifo()")
Signed-off-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Link: https://lore.kernel.org/r/20240409154253.3043822-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: max3100: Fix bitwise types</title>
<updated>2024-06-12T09:39:09+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2024-04-02T19:50:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=daae076ae946612b19e706d0b2ef3e091c1f4eea'/>
<id>daae076ae946612b19e706d0b2ef3e091c1f4eea</id>
<content type='text'>
[ Upstream commit e60955dbecb97f080848a57524827e2db29c70fd ]

Sparse is not happy about misuse of bitwise types:

  .../max3100.c:194:13: warning: incorrect type in assignment (different base types)
  .../max3100.c:194:13:    expected unsigned short [addressable] [usertype] etx
  .../max3100.c:194:13:    got restricted __be16 [usertype]
  .../max3100.c:202:15: warning: cast to restricted __be16

Fix this by choosing proper types for the respective variables.

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e60955dbecb97f080848a57524827e2db29c70fd ]

Sparse is not happy about misuse of bitwise types:

  .../max3100.c:194:13: warning: incorrect type in assignment (different base types)
  .../max3100.c:194:13:    expected unsigned short [addressable] [usertype] etx
  .../max3100.c:194:13:    got restricted __be16 [usertype]
  .../max3100.c:202:15: warning: cast to restricted __be16

Fix this by choosing proper types for the respective variables.

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: max3100: Update uart_driver_registered on driver removal</title>
<updated>2024-06-12T09:39:08+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2024-04-02T19:50:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fa84ca78b048dfb00df0ef446f5c35e0a98ca6a0'/>
<id>fa84ca78b048dfb00df0ef446f5c35e0a98ca6a0</id>
<content type='text'>
[ Upstream commit 712a1fcb38dc7cac6da63ee79a88708fbf9c45ec ]

The removal of the last MAX3100 device triggers the removal of
the driver. However, code doesn't update the respective global
variable and after insmod — rmmod — insmod cycle the kernel
oopses:

  max3100 spi-PRP0001:01: max3100_probe: adding port 0
  BUG: kernel NULL pointer dereference, address: 0000000000000408
  ...
  RIP: 0010:serial_core_register_port+0xa0/0x840
  ...
   max3100_probe+0x1b6/0x280 [max3100]
   spi_probe+0x8d/0xb0

Update the actual state so next time UART driver will be registered
again.

Hugo also noticed, that the error path in the probe also affected
by having the variable set, and not cleared. Instead of clearing it
move the assignment after the successfull uart_register_driver() call.

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 712a1fcb38dc7cac6da63ee79a88708fbf9c45ec ]

The removal of the last MAX3100 device triggers the removal of
the driver. However, code doesn't update the respective global
variable and after insmod — rmmod — insmod cycle the kernel
oopses:

  max3100 spi-PRP0001:01: max3100_probe: adding port 0
  BUG: kernel NULL pointer dereference, address: 0000000000000408
  ...
  RIP: 0010:serial_core_register_port+0xa0/0x840
  ...
   max3100_probe+0x1b6/0x280 [max3100]
   spi_probe+0x8d/0xb0

Update the actual state so next time UART driver will be registered
again.

Hugo also noticed, that the error path in the probe also affected
by having the variable set, and not cleared. Instead of clearing it
move the assignment after the successfull uart_register_driver() call.

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: max3100: Lock port-&gt;lock when calling uart_handle_cts_change()</title>
<updated>2024-06-12T09:39:08+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2024-04-02T19:50:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=865b30c8661924ee9145f442bf32cea549faa869'/>
<id>865b30c8661924ee9145f442bf32cea549faa869</id>
<content type='text'>
[ Upstream commit 77ab53371a2066fdf9b895246505f5ef5a4b5d47 ]

uart_handle_cts_change() has to be called with port lock taken,
Since we run it in a separate work, the lock may not be taken at
the time of running. Make sure that it's taken by explicitly doing
that. Without it we got a splat:

  WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0
  ...
  Workqueue: max3100-0 max3100_work [max3100]
  RIP: 0010:uart_handle_cts_change+0xa6/0xb0
  ...
   max3100_handlerx+0xc5/0x110 [max3100]
   max3100_work+0x12a/0x340 [max3100]

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 77ab53371a2066fdf9b895246505f5ef5a4b5d47 ]

uart_handle_cts_change() has to be called with port lock taken,
Since we run it in a separate work, the lock may not be taken at
the time of running. Make sure that it's taken by explicitly doing
that. Without it we got a splat:

  WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0
  ...
  Workqueue: max3100-0 max3100_work [max3100]
  RIP: 0010:uart_handle_cts_change+0xa6/0xb0
  ...
   max3100_handlerx+0xc5/0x110 [max3100]
   max3100_work+0x12a/0x340 [max3100]

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20240402195306.269276-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: 8520_mtk: Set RTS on shutdown for Rx in-band wakeup</title>
<updated>2024-05-30T07:43:59+00:00</updated>
<author>
<name>Pin-yen Lin</name>
<email>treapking@chromium.org</email>
</author>
<published>2024-04-24T12:58:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1f97ccd2c32ad8f0322e4fe3a291a61e509b3e5e'/>
<id>1f97ccd2c32ad8f0322e4fe3a291a61e509b3e5e</id>
<content type='text'>
commit 4244f830a56058ee0670d80e7ac9fd7c982eb480 upstream.

When Rx in-band wakeup is enabled, set RTS to true in mtk8250_shutdown()
so the connected device can still send message and trigger IRQ when the
system is suspended.

Fixes: 18c9d4a3c249 ("serial: When UART is suspended, set RTS to false")
Cc: stable &lt;stable@kernel.org&gt;
Signed-off-by: Pin-yen Lin &lt;treapking@chromium.org&gt;
Link: https://lore.kernel.org/r/20240424130619.2924456-1-treapking@chromium.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 4244f830a56058ee0670d80e7ac9fd7c982eb480 upstream.

When Rx in-band wakeup is enabled, set RTS to true in mtk8250_shutdown()
so the connected device can still send message and trigger IRQ when the
system is suspended.

Fixes: 18c9d4a3c249 ("serial: When UART is suspended, set RTS to false")
Cc: stable &lt;stable@kernel.org&gt;
Signed-off-by: Pin-yen Lin &lt;treapking@chromium.org&gt;
Link: https://lore.kernel.org/r/20240424130619.2924456-1-treapking@chromium.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: 8250_bcm7271: use default_mux_rate if possible</title>
<updated>2024-05-30T07:43:59+00:00</updated>
<author>
<name>Doug Berger</name>
<email>opendmb@gmail.com</email>
</author>
<published>2024-04-24T22:25:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f98bc68a3244beacf8092977782462429638d6eb'/>
<id>f98bc68a3244beacf8092977782462429638d6eb</id>
<content type='text'>
commit 614a19b89ca43449196a8af1afac7d55c6781687 upstream.

There is a scenario when resuming from some power saving states
with no_console_suspend where console output can be generated
before the 8250_bcm7271 driver gets the opportunity to restore
the baud_mux_clk frequency. Since the baud_mux_clk is at its
default frequency at this time the output can be garbled until
the driver gets the opportunity to resume.

Since this is only an issue with console use of the serial port
during that window and the console isn't likely to use baud
rates that require alternate baud_mux_clk frequencies, allow the
driver to select the default_mux_rate if it is accurate enough.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Cc: stable@vger.kernel.org
Signed-off-by: Doug Berger &lt;opendmb@gmail.com&gt;
Reviewed-by: Florian Fainelli &lt;florian.fainelli@broadcom.com&gt;
Tested-by: Florian Fainelli &lt;florian.fainelli@broadcom.com&gt;
Link: https://lore.kernel.org/r/20240424222559.1844045-1-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 614a19b89ca43449196a8af1afac7d55c6781687 upstream.

There is a scenario when resuming from some power saving states
with no_console_suspend where console output can be generated
before the 8250_bcm7271 driver gets the opportunity to restore
the baud_mux_clk frequency. Since the baud_mux_clk is at its
default frequency at this time the output can be garbled until
the driver gets the opportunity to resume.

Since this is only an issue with console use of the serial port
during that window and the console isn't likely to use baud
rates that require alternate baud_mux_clk frequencies, allow the
driver to select the default_mux_rate if it is accurate enough.

Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
Cc: stable@vger.kernel.org
Signed-off-by: Doug Berger &lt;opendmb@gmail.com&gt;
Reviewed-by: Florian Fainelli &lt;florian.fainelli@broadcom.com&gt;
Tested-by: Florian Fainelli &lt;florian.fainelli@broadcom.com&gt;
Link: https://lore.kernel.org/r/20240424222559.1844045-1-opendmb@gmail.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: sc16is7xx: fix bug in sc16is7xx_set_baud() when using prescaler</title>
<updated>2024-05-30T07:43:59+00:00</updated>
<author>
<name>Hugo Villeneuve</name>
<email>hvilleneuve@dimonoff.com</email>
</author>
<published>2024-04-30T20:04:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=671202e86739557e5612c132883c0246e02655cc'/>
<id>671202e86739557e5612c132883c0246e02655cc</id>
<content type='text'>
commit 8492bd91aa055907c67ef04f2b56f6dadd1f44bf upstream.

When using a high speed clock with a low baud rate, the 4x prescaler is
automatically selected if required. In that case, sc16is7xx_set_baud()
properly configures the chip registers, but returns an incorrect baud
rate by not taking into account the prescaler value. This incorrect baud
rate is then fed to uart_update_timeout().

For example, with an input clock of 80MHz, and a selected baud rate of 50,
sc16is7xx_set_baud() will return 200 instead of 50.

Fix this by first changing the prescaler variable to hold the selected
prescaler value instead of the MCR bitfield. Then properly take into
account the selected prescaler value in the return value computation.

Also add better documentation about the divisor value computation.

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Reviewed-by: Jiri Slaby &lt;jirislaby@kernel.org&gt;
Link: https://lore.kernel.org/r/20240430200431.4102923-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8492bd91aa055907c67ef04f2b56f6dadd1f44bf upstream.

When using a high speed clock with a low baud rate, the 4x prescaler is
automatically selected if required. In that case, sc16is7xx_set_baud()
properly configures the chip registers, but returns an incorrect baud
rate by not taking into account the prescaler value. This incorrect baud
rate is then fed to uart_update_timeout().

For example, with an input clock of 80MHz, and a selected baud rate of 50,
sc16is7xx_set_baud() will return 200 instead of 50.

Fix this by first changing the prescaler variable to hold the selected
prescaler value instead of the MCR bitfield. Then properly take into
account the selected prescaler value in the return value computation.

Also add better documentation about the divisor value computation.

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;
Reviewed-by: Jiri Slaby &lt;jirislaby@kernel.org&gt;
Link: https://lore.kernel.org/r/20240430200431.4102923-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tty: n_gsm: fix missing receive state reset after mode switch</title>
<updated>2024-05-30T07:43:58+00:00</updated>
<author>
<name>Daniel Starke</name>
<email>daniel.starke@siemens.com</email>
</author>
<published>2024-04-24T05:48:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fa5703bfa1e6002a1541cba93df7e312a2cf7ec0'/>
<id>fa5703bfa1e6002a1541cba93df7e312a2cf7ec0</id>
<content type='text'>
commit 70d7f1427afcf7fa2d21cb5a04c6f3555d5b9357 upstream.

The current implementation uses either gsm0_receive() or gsm1_receive()
depending on whether the user configured the mux in basic or advanced
option mode. Both functions share some state values over the same logical
elements of the frame. However, both frame types differ in their nature.
gsm0_receive() uses non-transparency framing, whereas gsm1_receive() uses
transparency mechanism. Switching between both modes leaves the receive
function in an undefined state when done during frame reception.

Fix this by splitting both states. Add gsm0_receive_state_check_and_fix()
and gsm1_receive_state_check_and_fix() to ensure that gsm-&gt;state is reset
after a change of gsm-&gt;receive.

Note that gsm-&gt;state is only accessed in:
- gsm0_receive()
- gsm1_receive()
- gsm_error()

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke &lt;daniel.starke@siemens.com&gt;
Link: https://lore.kernel.org/r/20240424054842.7741-2-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<pre>
commit 70d7f1427afcf7fa2d21cb5a04c6f3555d5b9357 upstream.

The current implementation uses either gsm0_receive() or gsm1_receive()
depending on whether the user configured the mux in basic or advanced
option mode. Both functions share some state values over the same logical
elements of the frame. However, both frame types differ in their nature.
gsm0_receive() uses non-transparency framing, whereas gsm1_receive() uses
transparency mechanism. Switching between both modes leaves the receive
function in an undefined state when done during frame reception.

Fix this by splitting both states. Add gsm0_receive_state_check_and_fix()
and gsm1_receive_state_check_and_fix() to ensure that gsm-&gt;state is reset
after a change of gsm-&gt;receive.

Note that gsm-&gt;state is only accessed in:
- gsm0_receive()
- gsm1_receive()
- gsm_error()

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke &lt;daniel.starke@siemens.com&gt;
Link: https://lore.kernel.org/r/20240424054842.7741-2-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<entry>
<title>tty: n_gsm: fix possible out-of-bounds in gsm0_receive()</title>
<updated>2024-05-30T07:43:58+00:00</updated>
<author>
<name>Daniel Starke</name>
<email>daniel.starke@siemens.com</email>
</author>
<published>2024-04-24T05:48:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b890d45aaf02b564e6cae2d2a590f9649330857d'/>
<id>b890d45aaf02b564e6cae2d2a590f9649330857d</id>
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commit 47388e807f85948eefc403a8a5fdc5b406a65d5a upstream.

Assuming the following:
- side A configures the n_gsm in basic option mode
- side B sends the header of a basic option mode frame with data length 1
- side A switches to advanced option mode
- side B sends 2 data bytes which exceeds gsm-&gt;len
  Reason: gsm-&gt;len is not used in advanced option mode.
- side A switches to basic option mode
- side B keeps sending until gsm0_receive() writes past gsm-&gt;buf
  Reason: Neither gsm-&gt;state nor gsm-&gt;len have been reset after
  reconfiguration.

Fix this by changing gsm-&gt;count to gsm-&gt;len comparison from equal to less
than. Also add upper limit checks against the constant MAX_MRU in
gsm0_receive() and gsm1_receive() to harden against memory corruption of
gsm-&gt;len and gsm-&gt;mru.

All other checks remain as we still need to limit the data according to the
user configuration and actual payload size.

Reported-by: j51569436@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218708
Tested-by: j51569436@gmail.com
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke &lt;daniel.starke@siemens.com&gt;
Link: https://lore.kernel.org/r/20240424054842.7741-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<pre>
commit 47388e807f85948eefc403a8a5fdc5b406a65d5a upstream.

Assuming the following:
- side A configures the n_gsm in basic option mode
- side B sends the header of a basic option mode frame with data length 1
- side A switches to advanced option mode
- side B sends 2 data bytes which exceeds gsm-&gt;len
  Reason: gsm-&gt;len is not used in advanced option mode.
- side A switches to basic option mode
- side B keeps sending until gsm0_receive() writes past gsm-&gt;buf
  Reason: Neither gsm-&gt;state nor gsm-&gt;len have been reset after
  reconfiguration.

Fix this by changing gsm-&gt;count to gsm-&gt;len comparison from equal to less
than. Also add upper limit checks against the constant MAX_MRU in
gsm0_receive() and gsm1_receive() to harden against memory corruption of
gsm-&gt;len and gsm-&gt;mru.

All other checks remain as we still need to limit the data according to the
user configuration and actual payload size.

Reported-by: j51569436@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218708
Tested-by: j51569436@gmail.com
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke &lt;daniel.starke@siemens.com&gt;
Link: https://lore.kernel.org/r/20240424054842.7741-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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