Messages in this thread Patch in this message | | | From | "Chris Snook" <> | Subject | [PATCH 2.4.33.2] enforce RLIMIT_NOFILE in poll() | Date | Thu, 31 Aug 2006 21:06:55 -0400 |
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From: Chris Snook <csnook@redhat.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@redhat.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;
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