* Re: compat_sys_sched_setaffinity()
2004-03-18 9:17 ` compat_sys_sched_setaffinity() Andrew Morton
@ 2004-03-18 9:46 ` Anton Blanchard
2004-03-18 23:08 ` compat_sys_sched_setaffinity() David S. Miller
0 siblings, 1 reply; 4+ messages in thread
From: Anton Blanchard @ 2004-03-18 9:46 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-arch
> It also seems to be broken with NR_CPUS > 32. The syscall API says
> (implies?) that CPU 0 is the LSB of *user_mask_ptr. On a big-endian 32-bit
> app, an attempt to bind to CPU #0 will end up binding to CPU #33, methinks.
>
>
> And it's potentially trying to copy more than `len' bytes from userspace so
> it might incorrectly return -EFAULT.
>
>
> And it's failing to check that len >= sizeof(cpumask_t). If the user
> passes in len==1, he gets bound to garbage CPUs.
Remember this patch? :) Dave and you had some concerns that it would
do bad things on little endian but I cant see why.
Anton
--
From anton@samba.org Thu Jan 22 02:27:40 2004
Date: Thu, 22 Jan 2004 02:27:40 +1100
From: Anton Blanchard <anton@samba.org>
To: linux-arch@vger.kernel.org
Subject: compat sched_affinity
Hi,
Ive got a patch in my local tree from Milton Miller that fixes the sched
affinity calls when NR_CPUS > 32.
Thoughts?
Anton
--
Patch from Milton Miller that adds the sched_affinity syscalls into the
compat layer.
gr16b-anton/kernel/compat.c | 88 +++++++++++++++++++++++++++++++++++++++-----
1 files changed, 79 insertions(+), 9 deletions(-)
diff -puN kernel/compat.c~compat_sys_sched_affinity kernel/compat.c
--- gr16b/kernel/compat.c~compat_sys_sched_affinity 2004-01-21 23:48:39.853282726 +1100
+++ gr16b-anton/kernel/compat.c 2004-01-21 23:48:39.861282640 +1100
@@ -381,6 +381,12 @@ compat_sys_wait4(compat_pid_t pid, compa
}
}
+/* for maximum compatability, we allow programs to use a single (compat)
+ * unsigned long bitmask if all cpus will fit. If not, you have to have
+ * at least the kernel size available.
+ */
+#define USE_COMPAT_ULONG_CPUMASK (NR_CPUS <= 8*sizeof(compat_ulong_t))
+
extern asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
unsigned long *user_mask_ptr);
@@ -388,18 +394,54 @@ asmlinkage long compat_sys_sched_setaffi
unsigned int len,
compat_ulong_t *user_mask_ptr)
{
- unsigned long kernel_mask;
+ cpumask_t kernel_mask;
mm_segment_t old_fs;
int ret;
- if (get_user(kernel_mask, user_mask_ptr))
- return -EFAULT;
+ if (USE_COMPAT_ULONG_CPUMASK) {
+ compat_ulong_t user_mask;
+
+ if (len < sizeof(user_mask))
+ return -EINVAL;
+
+ if (get_user(user_mask, user_mask_ptr))
+ return -EFAULT;
+
+ kernel_mask = cpus_promote(user_mask);
+ } else {
+ if (len < sizeof(kernel_mask))
+ return -EINVAL;
+
+ if (!access_ok(VERIFY_READ, user_mask_ptr, sizeof(kernel_mask)))
+ return -EFAULT;
+ else {
+ int i, j;
+ unsigned long *k, m;
+ compat_ulong_t um;
+
+ k = &cpus_coerce(kernel_mask);
+
+ for (i=0; i < sizeof(kernel_mask)/sizeof(m); i++) {
+ m = 0;
+
+ for (j = 0; j < sizeof(m)/sizeof(um); j++ ) {
+ if (__get_user(um, user_mask_ptr))
+ return -EFAULT;
+ user_mask_ptr++;
+ m <<= 4*sizeof(um);
+ m <<= 4*sizeof(um);
+ m |= um;
+ }
+ *k++ = m;
+ }
+ }
+ }
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = sys_sched_setaffinity(pid,
sizeof(kernel_mask),
- &kernel_mask);
+ (unsigned long *)&kernel_mask);
set_fs(old_fs);
return ret;
@@ -411,21 +453,49 @@ extern asmlinkage long sys_sched_getaffi
asmlinkage int compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
compat_ulong_t *user_mask_ptr)
{
- unsigned long kernel_mask;
+ cpumask_t kernel_mask;
mm_segment_t old_fs;
int ret;
+ if (len < (USE_COMPAT_ULONG_CPUMASK ? sizeof(compat_ulong_t)
+ : sizeof(kernel_mask)))
+ return -EINVAL;
+
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = sys_sched_getaffinity(pid,
sizeof(kernel_mask),
- &kernel_mask);
+ (unsigned long *)&kernel_mask);
set_fs(old_fs);
if (ret > 0) {
- ret = sizeof(compat_ulong_t);
- if (put_user(kernel_mask, user_mask_ptr))
- return -EFAULT;
+ if (USE_COMPAT_ULONG_CPUMASK) {
+ ret = sizeof(compat_ulong_t);
+ if (put_user(cpus_coerce(kernel_mask), user_mask_ptr))
+ return -EFAULT;
+ } else {
+ int i, j, err;
+ unsigned long *k, m;
+ compat_ulong_t um;
+
+ err = access_ok(VERIFY_WRITE, user_mask_ptr, ret);
+
+ k = &cpus_coerce(kernel_mask);
+
+ for (i=0; i < sizeof(kernel_mask)/sizeof(m) && !err; i++) {
+ m = *k++;
+
+ for (j = 0; j < sizeof(m)/sizeof(compat_ulong_t) && !err; j++ ) {
+ um = m;
+ err |= __put_user(um, user_mask_ptr);
+ user_mask_ptr++;
+ m >>= 4*sizeof(compat_ulong_t);
+ m >>= 4*sizeof(compat_ulong_t);
+ }
+ }
+ if (err)
+ ret = -EFAULT;
+ }
}
return ret;
^ permalink raw reply [flat|nested] 4+ messages in thread