[PATCH] sys_pselect7 vs compat_sys_pselect7 uaccess error handling
758333458aa719bfc26ec16eafd4ad3a9e96014d fixes the not checked copy_to_user
return value of compat_sys_pselect7. I ran into this too because of an old
source tree, but my fix would look quite a bit different to Andi's fix.
The reason is that the compat function IMHO should behave the very same as
the non-compat function if possible. Since sys_pselect7 does not return
-EFAULT in this specific case, change the compat code so it behaves like
sys_pselect7.
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/compat.c b/fs/compat.c
index 50624d4..8d0a001 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1835,9 +1835,12 @@
} while (!ret && !timeout && tsp && (ts.tv_sec || ts.tv_nsec));
- if (ret == 0 && tsp && !(current->personality & STICKY_TIMEOUTS)) {
+ if (tsp) {
struct compat_timespec rts;
+ if (current->personality & STICKY_TIMEOUTS)
+ goto sticky;
+
rts.tv_sec = timeout / HZ;
rts.tv_nsec = (timeout % HZ) * (NSEC_PER_SEC/HZ);
if (rts.tv_nsec >= NSEC_PER_SEC) {
@@ -1846,8 +1849,19 @@
}
if (compat_timespec_compare(&rts, &ts) >= 0)
rts = ts;
- if (copy_to_user(tsp, &rts, sizeof(rts)))
- ret = -EFAULT;
+ if (copy_to_user(tsp, &rts, sizeof(rts))) {
+sticky:
+ /*
+ * If an application puts its timeval in read-only
+ * memory, we don't want the Linux-specific update to
+ * the timeval to cause a fault after the select has
+ * completed successfully. However, because we're not
+ * updating the timeval, we can't restart the system
+ * call.
+ */
+ if (ret == -ERESTARTNOHAND)
+ ret = -EINTR;
+ }
}
if (ret == -ERESTARTNOHAND) {