• Rasmus Villemoes's avatar
    lib/vsprintf.c: eliminate potential race in string() · 34fc8b90
    Rasmus Villemoes authored
    If the string corresponding to a %s specifier can change under us, we
    might end up copying a \0 byte to the output buffer.  There might be
    callers who expect the output buffer to contain a genuine C string whose
    length is exactly the snprintf return value (assuming truncation hasn't
    happened or has been checked for).
    
    We can avoid this by only passing over the source string once, stopping
    the first time we meet a nul byte (or when we reach the given
    precision), and then letting widen_string() handle left/right space
    padding.  As a small bonus, this code reuse also makes the generated
    code slightly smaller.
    Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
    Cc: Al Viro <viro@ZenIV.linux.org.uk>
    Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Joe Perches <joe@perches.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Maurizio Lombardi <mlombard@redhat.com>
    Cc: Tejun Heo <tj@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    34fc8b90
vsprintf.c 63.1 KB