Imagine a trivial program doing
while (1) pipe(0);
this will cause lots of =EFAULTs for a while until we start getting
-EMFILE because of running out of descriptors. This is not nice because
the program may want to go on and open some other files etc. The proposed
solution is to close those two descriptors if copy_to_user() fails. I
understand, of course, that since we no longer hold the lock some other
thread may have reused the descriptors but such potential race condition
is (imho) much better than to have a blatant running out of resources in
the failing code path of sys_pipe().
The copy of the patch (for all archs that are affected) is on:
http://www.ocston.org/~tigran/patches/pipe-2.3.29.patch
Regards,
------
Tigran A. Aivazian | http://www.sco.com
Escalations Research Group | tel: +44-(0)1923-813796
Santa Cruz Operation Ltd | http://www.ocston.org/~tigran
diff -urN -X dontdiff linux/arch/arm/kernel/sys_arm.c 2329-pipe/arch/arm/kernel/sys_arm.c
--- linux/arch/arm/kernel/sys_arm.c Wed Nov 24 06:23:11 1999
+++ 2329-pipe/arch/arm/kernel/sys_arm.c Wed Nov 24 14:25:53 1999
@@ -43,8 +43,11 @@
error = do_pipe(fd);
unlock_kernel();
if (!error) {
- if (copy_to_user(fildes, fd, 2*sizeof(int)))
+ if (copy_to_user(fildes, fd, 2*sizeof(int))) {
error = -EFAULT;
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ }
}
return error;
}
diff -urN -X dontdiff linux/arch/i386/kernel/sys_i386.c 2329-pipe/arch/i386/kernel/sys_i386.c
--- linux/arch/i386/kernel/sys_i386.c Wed Nov 3 19:31:09 1999
+++ 2329-pipe/arch/i386/kernel/sys_i386.c Wed Nov 24 14:24:58 1999
@@ -35,8 +35,11 @@
error = do_pipe(fd);
unlock_kernel();
if (!error) {
- if (copy_to_user(fildes, fd, 2*sizeof(int)))
+ if (copy_to_user(fildes, fd, 2*sizeof(int))) {
error = -EFAULT;
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ }
}
return error;
}
diff -urN -X dontdiff linux/arch/m68k/kernel/sys_m68k.c 2329-pipe/arch/m68k/kernel/sys_m68k.c
--- linux/arch/m68k/kernel/sys_m68k.c Tue Jan 19 18:58:34 1999
+++ 2329-pipe/arch/m68k/kernel/sys_m68k.c Wed Nov 24 14:26:19 1999
@@ -37,8 +37,11 @@
lock_kernel();
error = do_pipe(fd);
if (!error) {
- if (copy_to_user(fildes, fd, 2*sizeof(int)))
+ if (copy_to_user(fildes, fd, 2*sizeof(int))) {
error = -EFAULT;
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ }
}
unlock_kernel();
return error;
diff -urN -X dontdiff linux/arch/ppc/kernel/syscalls.c 2329-pipe/arch/ppc/kernel/syscalls.c
--- linux/arch/ppc/kernel/syscalls.c Wed Sep 8 18:59:07 1999
+++ 2329-pipe/arch/ppc/kernel/syscalls.c Wed Nov 24 14:27:06 1999
@@ -188,8 +188,11 @@
error = do_pipe(fd);
unlock_kernel();
if (!error) {
- if (copy_to_user(fildes, fd, 2*sizeof(int)))
+ if (copy_to_user(fildes, fd, 2*sizeof(int))) {
error = -EFAULT;
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ }
}
return error;
}
diff -urN -X dontdiff linux/arch/sh/kernel/sys_sh.c 2329-pipe/arch/sh/kernel/sys_sh.c
--- linux/arch/sh/kernel/sys_sh.c Sat Nov 6 18:40:31 1999
+++ 2329-pipe/arch/sh/kernel/sys_sh.c Wed Nov 24 14:27:28 1999
@@ -37,8 +37,11 @@
error = do_pipe(fd);
unlock_kernel();
if (!error) {
- if (copy_to_user(fildes, fd, 2*sizeof(int)))
+ if (copy_to_user(fildes, fd, 2*sizeof(int))) {
error = -EFAULT;
+ sys_close(fd[0]);
+ sys_close(fd[1]);
+ }
}
return error;
}
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