lib/vsprintf.c: improve sanity check in vsnprintf()

On 64 bit, size may very well be huge even if bit 31 happens to be 0.
Somehow it doesn't feel right that one can pass a 5 GiB buffer but not a
3 GiB one.  So cap at INT_MAX as was probably the intention all along.
This is also the made-up value passed by sprintf and vsprintf.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 98ad170b10e0d0eebedadc4e05620f110f58213c..cf12ba86205c096eea6543e3c2850e384ca139c1 100644 (file)
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1727,7 +1727,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 
        /* Reject out-of-range values early.  Large positive sizes are
           used for unknown buffer sizes. */
-       if (WARN_ON_ONCE((int) size < 0))
+       if (WARN_ON_ONCE(size > INT_MAX))
                return 0;
 
        str = buf;