linux-kernel - [PATCH 2.4.33.2] enforce RLIMIT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 31 Aug 2006 21:06:55 -0400
From:	"Chris Snook" <csnook@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	willy@...ds.org
Subject: [PATCH 2.4.33.2] enforce RLIMIT_NOFILE in poll()

From: Chris Snook <csnook@...hat.com>

POSIX states that poll() shall fail with EINVAL if nfds > OPEN_MAX.  In this
context, POSIX is referring to sysconf(OPEN_MAX), which is the value of
current->rlim[RLIMIT_NOFILE].rlim_cur, not the compile-time constant which
happens to be named OPEN_MAX.  The current code will permit polling up to 1024
file descriptors even if RLIMIT_NOFILE is less than 1024, which POSIX forbids.
 The current code also breaks polling greater than 1024 file descriptors if
the process has less than 1024 valid descriptors, even if RLIMIT_NOFILE >
1024.  While it is silly to poll duplicate or invalid file descriptors, POSIX
permits this, and it worked circa 2.4.18, and currently works up to 1024.
This patch directly checks the RLIMIT_NOFILE value, and permits exactly what
POSIX suggests, no more, no less.

Signed-off-by: Chris Snook <csnook@...hat.com>
---

diff -urNp linux-2.4.33.2-orig/fs/select.c linux-2.4.33.2-patch/fs/select.c
--- linux-2.4.33.2-orig/fs/select.c	2006-08-22 16:13:54.000000000 -0400
+++ linux-2.4.33.2-patch/fs/select.c	2006-08-31 13:43:39.000000000 -0400
@@ -417,7 +417,7 @@ asmlinkage long sys_poll(struct pollfd *
 	int nchunks, nleft;

 	/* Do a sanity check on nfds ... */
-	if (nfds > current->files->max_fdset && nfds > OPEN_MAX)
+	if (nfds > current->rlim[RLIMIT_NOFILE].rlim_cur)
 		return -EINVAL;

 	if (timeout) {

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/