mm/nommu.c: add additional check for vread() just like vwrite() has done

vwrite() checks for overflow. vread() should do the same thing.

Since vwrite() checks the source buffer address, vread() should check
the destination buffer address.

Signed-off-by: Chen Gang <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/nommu.c b/mm/nommu.c
index 298884dcd6e71e4723a203a82f1613cbfcec19ec..1898b2fe9da5eefdc3b33823a3cd23d2a401118f 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -282,6 +282,10 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
 
 long vread(char *buf, char *addr, unsigned long count)
 {
+       /* Don't allow overflow */
+       if ((unsigned long) buf + count < count)
+               count = -(unsigned long) buf;
+
        memcpy(buf, addr, count);
        return count;
 }