[PATCH] stty: valid ispeed and ospeed arguments

[Pádraig Brady]

* src/stty.c (apply_settings): Validate [io]speed arguments
against the internal accepted set.
(set_speed): Check the cfset[io]speed() return value so
that we validate against the system supported set.
* tests/misc/stty-invalid.sh: Add a test case.
* NEWS: Mention the bug fix.
Reported in https://bugs.debian.org/1018790
---
 NEWS                       |  5 +++++
 src/stty.c                 | 29 +++++++++++++++++++++++++----
 tests/misc/stty-invalid.sh |  3 +++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/NEWS b/NEWS
index ab1a2ef91..db5150824 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,11 @@ GNU coreutils NEWS                                    -*- 
outline -*-
   long been documented to be platform-dependent.
   [bug introduced 1999-05-02 and only partly fixed in coreutils-8.14]
 
+  stty ispeed and ospeed options no longer accept and silently ignore
+  invalid speed arguments.  Now they're validated against both the
+  general accepted set, and the system supported set of valid speeds.
+  [This bug was present in "the beginning".]
+
 ** Changes in behavior
 
   'cp --reflink=always A B' no longer leaves behind a newly created
diff --git a/src/stty.c b/src/stty.c
index 3b6a592a9..3d515223e 100644
--- a/src/stty.c
+++ b/src/stty.c
@@ -1159,6 +1159,11 @@ apply_settings (bool checking, char const *device_name,
             {
               check_argument (arg);
               ++k;
+              if (string_to_baud (settings[k]) == (speed_t) -1)
+                {
+                  error (0, 0, _("invalid ispeed %s"), quote (settings[k]));
+                  usage (EXIT_FAILURE);
+                }
               if (checking)
                 continue;
               set_speed (input_speed, settings[k], mode);
@@ -1169,6 +1174,11 @@ apply_settings (bool checking, char const *device_name,
             {
               check_argument (arg);
               ++k;
+              if (string_to_baud (settings[k]) == (speed_t) -1)
+                {
+                  error (0, 0, _("invalid ospeed %s"), quote (settings[k]));
+                  usage (EXIT_FAILURE);
+                }
               if (checking)
                 continue;
               set_speed (output_speed, settings[k], mode);
@@ -1696,13 +1706,24 @@ set_control_char (struct control_info const *info, char 
const *arg,
 static void
 set_speed (enum speed_setting type, char const *arg, struct termios *mode)
 {
-  speed_t baud;
+  /* Note cfset[io]speed(), do not check with the device,
+     and only check whether the system logic supports the specified speed.
+     Therefore we don't report the device name in any errors.  */
+
+  speed_t baud = string_to_baud (arg);
+
+  assert (baud != (speed_t) -1);
 
-  baud = string_to_baud (arg);
   if (type == input_speed || type == both_speeds)
-    cfsetispeed (mode, baud);
+    {
+      if (cfsetispeed (mode, baud))
+        die (EXIT_FAILURE, 0, "unsupported ispeed %s", quotef (arg));
+    }
   if (type == output_speed || type == both_speeds)
-    cfsetospeed (mode, baud);
+    {
+      if (cfsetospeed (mode, baud))
+        die (EXIT_FAILURE, 0, "unsupported ospeed %s", quotef (arg));
+    }
 }
 
 #ifdef TIOCGWINSZ
diff --git a/tests/misc/stty-invalid.sh b/tests/misc/stty-invalid.sh
index 58e51311d..af49b8d89 100755
--- a/tests/misc/stty-invalid.sh
+++ b/tests/misc/stty-invalid.sh
@@ -50,6 +50,9 @@ if tty -s </dev/tty; then
   returns_ 1 stty eol -F/dev/tty eol || fail=1
 fi
 
+# coreutils <= 9.1 would not validate speeds to ispeed or ospeed
+returns_ 1 stty ispeed 420 || fail=1
+
 # Just in case either of the above mistakenly succeeds (and changes
 # the state of our tty), try to restore the initial state.
 stty $saved_state || fail=1
-- 
2.26.2