[PATCH] max_fds race in select().

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We can end up with the user getting more fds tban they asked for...

Unlikely, but possible,
Rusty.
--- linux-2.4.4-official/fs/select.c Thu Feb 22 14:25:36 2001
+++ working-2.4.4-rcu/fs/select.c Fri May 4 14:06:39 2001
@@ -260,7 +260,7 @@
         fd_set_bits fds;
         char *bits;
         long timeout;
- int ret, size;
+ int ret, size, max_fdset;
 
         timeout = MAX_SCHEDULE_TIMEOUT;
         if (tvp) {
@@ -285,8 +285,10 @@
         if (n < 0)
                 goto out_nofds;
 
- if (n > current->files->max_fdset)
- n = current->files->max_fdset;
+ /* max_fdset can increase, so grab it once to avoid race */
+ max_fdset = current->files->max_fdset;
+ if (n > max_fdset)
+ n = max_fdset;
 
         /*
          * We need 6 bitmaps (in/out/ex for both incoming and outgoing),

--
Premature optmztion is rt of all evl. --DK
-
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• Next message: Alexander Viro: "Re: [PATCH] max_fds race in select()."
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This archive was generated by hypermail 2b29 : Mon May 07 2001 - 21:00:19 EST