Re: [PATCH] lib: Fix bug in int_sqrt() for 64 bit longs
From: Eric Dumazet
Date: Fri Jan 06 2006 - 01:41:55 EST
Peter Williams a écrit :
The implementation of int_sqrt() assumes that longs have 32 bits. On
systems that have 64 bit longs this will result in gross errors when the
argument to the function is greater than 2^32 - 1 on such systems. I
doubt whether any such use is currently made of int_sqrt() but the
attached patch fixes the problem anyway.
Signed-off-by: Peter Williams <pwil3058@xxxxxxxxxxxxxx>
------------------------------------------------------------------------
Index: GIT-warnings/lib/int_sqrt.c
===================================================================
--- GIT-warnings.orig/lib/int_sqrt.c 2005-10-25 13:55:22.000000000 +1000
+++ GIT-warnings/lib/int_sqrt.c 2006-01-06 14:29:19.000000000 +1100
@@ -15,7 +15,7 @@ unsigned long int_sqrt(unsigned long x)
op = x;
res = 0;
- one = 1 << 30;
+ one = 1 << (BITS_PER_LONG - 2);
while (one > op)
one >>= 2;
Are you sure it works ?
I would have writen :
one = 1L << (BITS_PER_LONG - 2);
Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/