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If an application closes one of its stdio descriptors (0..2),

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an excessive close() on one of these descriptors would cause
a memory for this descriptor to be allocated in the internal
descriptor table.  When this descriptor gets used again, e.g.
through the call to open() or socket(), the descriptor would
be erroneously left in the blocking mode, and the whole
application would get stuck on a blocking operation, e.g.,
in accept(2).

Prevent this bug from happening by disallowing close() against
non-active descriptors (return -1 and set errno to EBADF in
this case).

Reviewed by:	deischen
Approved by:	re (scottl)
This commit is contained in:
Ruslan Ermilov 2003-05-31 05:20:44 +00:00
parent 2450346579
commit d635dc4671
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=115421
1 changed files with 4 additions and 2 deletions
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6
lib/libc_r/uthread/uthread_close.c
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@ -49,9 +49,11 @@ _close(int fd)
struct stat sb;
struct fd_table_entry *entry;
if ((fd == _thread_kern_pipe[0]) || (fd == _thread_kern_pipe[1])) {
if ((fd == _thread_kern_pipe[0]) || (fd == _thread_kern_pipe[1]) ||
(_thread_fd_table[fd] == NULL)) {
/*
* Don't allow silly programs to close the kernel pipe.
* Don't allow silly programs to close the kernel pipe
* and non-active descriptors.
*/
errno = EBADF;
ret = -1;