add: protection against overflow in read/write

3 files changed, 92 insertions, 3 deletions

diff --git a/man/rb_read.3 b/man/rb_read.3
index 4fe2797..1568d5d 100644
--- a/man/rb_read.3
+++ b/man/rb_read.3
@@ -55,6 +55,27 @@ number than call it in a loop with
 .I count
 == 1.
 .PP
+Altough
+.I count
+is of
+.B size_t
+type, functions will not read more than
+.B LONG_MAX
+elements.
+If
+.I count
+is bigger than
+.B LONG_MAX
+it will be set to
+.B LONG_MAX
+internaly anyway.
+Also make sure that formula
+.IR count * rb->object_size
+does not exceed
+.B size_t
+type or you will overflow internal integer and that will result in Undefined
+Behaviour.
+.PP
 By default buffer works in single-threaded mode.
 In this mode all calls on
 .I rb
@@ -259,11 +280,17 @@ Reading frames by multiple parsers. Error handling ommited for clarity.
              * NOTE: rb will now be locked from writing, only
              * this thread will be able to write to rb, don't
              * try to call another rb_write() function, it will
-             * be blocked until this function return (SIZE_MAX
-             * bytes have been read from fd) or error occurs
+             * be blocked until this function returns - and it
+             * may take a while to read LONG_MAX / OBJECT_SIZE.
+             *
+             * LONG_MAX / OBJECT_SIZE is passed as count because
+             * we want this function to be called as rarely as
+             * possible, and still we don't want to overflow
+             * internal integer. OBJECT_SIZE is size of a single
+             * rb object set during creation of rb
              */
 
-            if (rb_fd_write(rb, fd, SIZE_MAX) == -1)
+            if (rb_fd_write(rb, fd, LONG_MAX / OBJECT_SIZE) == -1)
             {
                 if (errno == ECANCELED)
                 {
diff --git a/man/rb_write.3 b/man/rb_write.3
index a052013..2c87ca4 100644
--- a/man/rb_write.3
+++ b/man/rb_write.3
@@ -58,6 +58,27 @@ number instead of calling it in a loop with
 .I count
 == 1.
 .PP
+Altough
+.I count
+is of
+.B size_t
+type, functions will not write more than
+.B LONG_MAX
+elements.
+If
+.I count
+is bigger than
+.B LONG_MAX
+it will be set to
+.B LONG_MAX
+internaly anyway.
+Also make sure that formula
+.IR count * rb->object_size
+does not exceed
+.B size_t
+type or you will overflow internal integer and that will result in Undefined
+Behaviour.
+.PP
 By default
 .B rb
 works in single-threaded mode.
diff --git a/rb.c b/rb.c
index a16c7ec..aa0ef4c 100644
--- a/rb.c
+++ b/rb.c
@@ -53,6 +53,7 @@
 #endif /* HAVE_ASSERT_H */
 
 #include <errno.h>
+#include <limits.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -2056,6 +2057,16 @@ long rb_recv
     VALID(EINVAL, buffer);
     VALID(EINVAL, rb->buffer);
 
+    if (count > (size_t)LONG_MAX)
+    {
+        /*
+         * function cannot read more than LONG_MAX count of  elements,  trim
+         * users count to acceptable value
+         */
+
+        count = LONG_MAX;
+    }
+
 #if ENABLE_THREADS
     if ((rb->flags & O_MULTITHREAD) == 0)
     {
@@ -2133,6 +2144,16 @@ long rb_posix_recv
     VALID(EINVAL, rb->buffer);
     VALID(EINVAL, fd >= 0);
 
+    if (count > (size_t)LONG_MAX)
+    {
+        /*
+         * function cannot read more than LONG_MAX count of  elements,  trim
+         * users count to acceptable value
+         */
+
+        count = LONG_MAX;
+    }
+
 #   if ENABLE_THREADS
 
     if ((rb->flags & O_MULTITHREAD) == 0)
@@ -2233,6 +2254,16 @@ long rb_send
     VALID(EINVAL, buffer);
     VALID(EINVAL, rb->buffer);
 
+    if (count > (size_t)LONG_MAX)
+    {
+        /*
+         * function cannot read more than LONG_MAX count of  elements,  trim
+         * users count to acceptable value
+         */
+
+        count = LONG_MAX;
+    }
+
 #if ENABLE_THREADS
     if ((rb->flags & O_MULTITHREAD) == 0)
     {
@@ -2294,6 +2325,16 @@ long rb_posix_send
     VALID(EINVAL, rb->buffer);
     VALID(EINVAL, fd >= 0);
 
+    if (count > (size_t)LONG_MAX)
+    {
+        /*
+         * function cannot read more than LONG_MAX count of  elements,  trim
+         * users count to acceptable value
+         */
+
+        count = LONG_MAX;
+    }
+
 #   if ENABLE_THREADS
 
     if ((rb->flags & O_MULTITHREAD) == 0)